The Great Rock
The Budapest Zoo has twice changed dramatically during the past hundred years: first between 1907 and 1912, when the totally obsolete Zoo underwent a profound reconstruction, and for the second time between 1996 and 2008, when after nearly 90 years of “use” it was completely renovated and modernised, in line with the requirements of modern animal zoos. In the second stage of the reconstruction works between 2006 and 2008, in addition to the creation and modernisation of numerous new animal housing facilities, amongst them the largest enclosure of the Zoo, the Savannah, the area around the Great Rock was also renovated.
The new developments such as the promenades of the Great Rock which have been closed to visitors for almost 50 years were opened to the public in the spring of 2008. It was the first time since World War II that visitors could walk these paths, admiring the exceptional panorama that they open up. The Tejcsarnok (Dairy), designed by Károly Kós and Dezső Zrumeczky in the side of the Great Rock has also been re-built as part of the reconstruction programme.
The History of the Construction of the Great Rock
In June 1909, 43 years after the Állat- és Növényhonosító Társaság (Animal and Plant Naturalization Society) was founded, the capital took possession of the Zoo with the aim of establishing new animal demonstration areas and buildings- a modern zoo in line with the thinking of the time, the popularity of which had declined over the previous decade.
The general assembly of the municipal board of the Capital voted to offer 1,212,000 then later 1,788,000 kroner for the developments, electing a committee at the same time for directing the works. Dr Adolf Lendl was appointed for reviewing and inspecting the zoological work and Dr Kornél Neuschloss for the construction and technical works. The engineering work for the transforming the area of the garden was carried out by the engineer Gyula Végh, who with Károly Kós and Dezső Zrumeczky had the new buildings designed by several participating young architects. Ilsemann Keresztély, the Director of the Garden took a role in the transformation of the park and in the establishment of the long desired Pálmaház (Palm House).
In order for the area to appear larger and to show the animals in an environment similar to that of their natural habitat, the construction of two artificial rocks, at the time named Hill “A” and Hill “B”, were also included in the ideas.
Hill “A” is in the shape of a limestone range with a dolomite peak; its area is 4,700 square meters with an internal space of 38,850 m3.
“… we erect a high rocky hill… and it will be built in the characteristic grey limestone shapes of karst areas. It large area will provide a varied appearance and if we insert small grassy meadows and water-washed gullies between the steep rock walls and the ragged blocks leading down with a wide valley, it will thus naturally connect the rocky eminence. There will be animals all over it and in the deeper sections trees and bushes can develop.” (Lendl)
Two 1:200 scale models were made of the rocks for the planning and design phase, and for the construction work further models in more detail on a1:25 meter scale. In order to find the correct ratio, a scale model was also made for the whole of the planned garden.
The shape of the hill defined the reinforced concrete frame holding up the shell. The task was to connect the points in space and to create statically purposeful shapes that fitted onto these. Amongst the different structural solutions, the dome and the spatial trusses suggest the wooden frame form solution applied by Karl Hagenbeck, previously director of the Berlin Zoo, and the constructions of the different supporting walls as well as the curved supports suggest an enthusiastic experimenting mood.
In addition the structure had to be scaled for the public that conquered the ridge and also the snow load, as well as the soil that was used on the plateau between the two peaks (20 m and 34 m). The central inner space with a 31.80 m tension length and the suspended dome above it was unique in its own right at the time. Its height at the protective collar reached 16.80 m. The form of the eight curved main girders followed the thrust line; therefore the load on the rings holding them together was minimal. The basal ring was even omitted with the foundations sufficiently reinforced instead. The staggered design of the external surfaces of the supports enabled the joining of the posts and beams of the spatial trusses.
The dome would have provided a home for the water storage, which would have been filled from the drilled wells of the Garden providing a water supply to the area. However by the time the rock was completed, the town’s water supply had reached the Városliget, therefore it became unnecessary. The tank that can be seen today was initially planned as storage in case of fire but due to a lack of funds the idea did not actually come to fruition and the tank has never been filled. During construction the dimensions of the hill at the lion house was altered, thus creating another new large inner space. The former are connected by a structure that is made up of 8 curved supports between 9 and 13 m long. The supports for the passages everywhere are reinforced concrete plates that rest on a beam frame.
“… and the largest cats, the lions and tigers (no doubt we can expect many specimens, as these are the more common species available) according to the Stellingen method are under an open sky on the southern side of the hill erected from limestone, with sloping yards surrounded by a wide ditch and enclosed at the back by high stone walls. The large bears will be located similarly at the northern base of the same hill. With all certainty we will have many specimens in 3 to 4 species…
Several paths lead through the heights of the hill. We bridge the gorges and turn walking around the peaks: from the highest points of the hill beautiful views open up to the fresh and green areas below… and as we cross to this side of the hill, another view opens up to us; there are different animals amongst the rocks and in the valley that leads downwards. In places caprine and ovine animals are grazing freely in the small meadows inserted between the naked boulders; wild goat species from Asia and Africa and moufflon climb to the ridges to jump from there as we have seen in the Stellingen Zoo. The grids and the fences are not visible to the visitors amongst the rocks and bushes, for that reason the animals appear as if they lived free in the wild. The environment around them is developed in a masterful way; the animal houses are also hidden or at least their view does not disturb the audience.” (Lendl)
The construction commenced in 1909. The work was awarded in a tender to György Pohl’s company. The rock was continuously built by 150-220 people for 3 years, fifty of them alone carried out the shuttering works, with eight thousand cubic meters of concrete being used. The progress of the support was continuously followed by the construction of the outer shell. Cantilever beams and steels that projected from the reinforced concrete scaffolding were used for supporting the hill’s covering shell. This was made of 6-12 centimetres of a Portland cement wire lattice structure (3.5 parts Danube sand, 1 part Portland cement) covering nineteen thousand m2 with pig hair mixed into the mortar to achieve better plasticity. Fine particle concrete was applied to the scaffolding.
The drainage for the rock was developed with great care, applying impermeable concrete to the sensitive areas. In order to prevent cracking in the rocks, expansion joints were included in many places in a way that they would appear to the external observer as natural formations. The foundation, due to the high water table, was from compacted concrete with the walls and floors of the pens of reinforced concrete to prevent the animals from scraping their way through it.
Leaks, internal condensation and damage from World War II together with their poor restoration, as well as the erosion and the corrosive effect of the air pollution of several decades all damaged the support and crustal structure of the rock. On the surface of the crumbling concrete pitting and cracks appeared as well as corrosion of the reinforced steel surfaces. Despite all this the support structure remained in adequate condition until the 21st century. However the shell structure became largely carbonated and full renovation became unavoidable by the turn of the millennia. During the wide ranging renovation works that were carried out between 2006 and 2008, care had to be taken to ensure the external surface remained waterproof and to provide for ventilation of the inner spaces.
The rocks were the most modern animal display spaces of their time
The story of the use of the artificial rocks in the zoo, as animal enclosures started in Zürich. Urs Eggenschwiler, a sculptor who befriended the animals in Zürich designed an artificial rock for the Zürich Zoo. The plan was not implemented there, however the idea appealed to Karl Hagenbeck, the director of the Hamburg Zoo and so the first zoo artificial rocks were built in the Hamburg-Stellingen Zoo with the application of the “panorama-display”. The idea then was taken up by several zoos at the time, and was also the case in Budapest. This was supported by a visit of the members of the “Zoo Building Committee” prior to the great reconstructions of 1909-1912, to Hamburg as part of a study tour.
In those few places, where the artificial rocks still survive today, they are treasured as the specialities of previous times from Hamburg to Antwerp and from Barcelona to Buenos Aires. However artificial rock hills of similar size to the ones in Budapest are only found in the Vincennes Zoo in Paris. These were made two decades later and were opened in 1931 with the highest peak; their “Great Rock” at 72 m. In the inside however there are no really usable spaces; neither does the finish of its surface show such details as those in Budapest. Its reconstruction was completed in 1997.
The Magyar Királyi Földtani Intézet (Hungarian Royal Institute of Geology) provided expert guidelines for the preparation of the patterns of the artificial rock and for shaping the granite, gneiss, limestone, dolomite, sandstone, basalt and trachyte stones. A geologist and a sculptor was said to have directed the foremen at the construction and in order for the work to resemble a natural cliff as much as possible, photos and surveys of the “Egyeskő” peak in Transylvania served as a model.
In the Budapest Zoo the role of the rocks was partially to create an aesthetic, nature like display of the animals, as well as to develop exhibition spaces that were considered most modern at the time. Their most important function however was to optically divide the area that was already constrained and to provide an extended walkway. Everybody is surprised that it is only 10 hectares that can be viewed by visitors in Budapest (both amongst the zoos of European capitals and of larger Hungarian towns the zoo at Budapest is one of the smallest). The Gardens are perceived as a much larger space when walking around than in reality, thanks to the artificial rocks and successful landscaping.
The construction of the "rock hills" was followed with great interest by the entire country. One of the contemporary issues of "Hungarian Architectural Art" wrote regarding the two artificial rocks:
"Real art was needed to build the two approximately 40 m high rocky hills in the middle of the area and in the varied form as they stand today (these large hills were entirely made of cement concrete and are empty inside with the internal cages for the animals invisibly included there). Between the artificial worn stone boulders and rocks built in the form characteristic of the grey rocks of Karst areas, there are lawned little meadows, water washed gorges and caves, which lead down to the flat areas surrounding the hill and thus naturally connect the rocky heights. The other hill, the majority of which is made up of artificial granite and gneiss sheets stands in the middle of the lake, the level of which was lowered by 2-3 m and by this the entire environment of it was changed, which up till then had been a little unnatural and rather deserted". (Hungarian Architectural Art)
Walkways were designed for the top of the rocks, from where beautiful views opened up both to the zoo as well as the city. The main walkway started from the Transylvanian style shingled Central Dairy (Tejcsarnok), the purpose of which originally was to popularise milk consumption and healthy eating. The flock of goats they regularly milked and the produce was offered for sale on site. The Kós-Zrumetzky building was used for different purposes after World War II, the Szikla Vendéglő (Rock Inn) moved here, and it provided space for an office where it was said that the Prime Minister, Péter Boross had also worked in, although later it was demolished. The Tejcsarnok was rebuilt in 2008 to its former beauty.
Around 1910, with the exception of church towers, there were very few buildings with a similar height to that of the Great Rock in Pest, and none of which were open to the public. Unfortunately, visitors were not able to use the rocky walkways for very long, as the steps leading onto the rock were closed. This was mainly due to the risk of accidents, as these pathways became dangerous over time due to the deterioration in the condition of the rocks. Originally there was a walkway up to the Great Rock from three sides, however due to the reconstruction of the animal display areas around the rock, today only two are usable. Unfortunately the idea of animals wondering around freely was also unsuccessful, as it was impossible to keep the Caprids the hill, for them the plant rarities of the park were far more attractive and it seemed the more expensive a plant was the more the goats enjoyed chewing it.
The greatest novelty in accommodating the animals was the display of the large predatory mammals in dry trenches and around artificial rock, the advantages of which the members of the Committee had already got to know during their foreign study trips prior to the planning. The idea of a display method using “panoramic runs" was born in the Hagenbeck-type zoo in Hamburg, namely, that the animals are presented to the visitors in an environment that looks natural, without bars and fences, separated by dry or wet trenches. The audience does not notice the deep trench due to its hidden position, however they are safely separated from the animals by its depth and width.
The lion enclosure was developed in the larger, 35m high rock construction with this method. “Here however we meet a great surprise. We find two extensive caves in the hill side, both with wide openings so we can easily see into their depths. The sides are a steep ravine and we see in these two caves the same lions and tigers that were outside, here however the dangerous animals are completely free. They stand fifteen steps away in front of us in the cave. Tigers in one and lions in the other, although they cannot harm the audience or leap out to the path, as despite the absence of bars or a fence keeping them there, the front of the caves are invisibly separated from the area in the foreground with a wide and deep trench, which even the best leap will not allow an escape.” (Guide)
The three cave-like spaces for the bears were similarly formed on the northern side. (A lesser cage was also made for the “smaller bears”, in which, once they had grown, they were miserably crammed until the demolition of them in 1997.) There are also bears living in this area today, although instead of the 3-4 different bear species or subspecies of the past, only one type of bear given larger runs and richer in environmental elements is housed. The large cats moved out from the former lion and tiger caves a long time ago. The larger of the caves became part of the new gorilla area of 1200 square meters, the smaller can be viewed, as a zoological monument, in its original condition with those interested also being able to look into the giant trench.
The arctic panorama at the Small Rock, forming a 22m high granite peak, was also designed based on the Hagenbeck method. There however for an even more impressive view, the seals’ pool was placed in front of the trench for the polar bears. During the design phase consideration was also given to the orientation of the runs, the direction of the wind, as well as the position and dimensions of the plateaus and caves. In the animal display east of the Great Rock a joint run was developed, which also counted as a novelty at the time, and some characteristic herbivores of the African Savannah, birds, ostriches, zebras and antelopes were shown together.
The display concept of the newly restored Zoo was developed by Dr Adolf Lendl. In connection with determining the location of the animal houses and runs he himself wrote: “…species more similar and belonging to each other were put together according to families and orders, as it is required by scientific taxonomy.” Lendl’s concept that was considered modern a hundred years ago has been since re-evaluated and the Zoo successfully rid itself of the previous “menagerie” image. More than this, it has developed into a complex cultural institute. Not only because the collection living there is no longer organised on a taxonomic or “stamp collecting” basis, but in addition to the animal and plant species, ecological units are also displayed. It has progressed far beyond this and has developed significant services in the fields of the arts, education or other areas of culture.
The menagerie – zoo – animal park – bio park – eco park evolutionary steps have also been walked by the profession in Budapest, however the circumstances, the location, the demands of the audience and the institutional traditions require a different approach. Ecological display today is an accepted objective; animal and plant species living in a geographical unit or in similar biotopes are displayed closer together. There are clear directing ideas, which emphasis this modern message. Besides the live exhibitions such ideas are for example for the Zoo to be a model for environment friendly operation or to suitably preserve its unique architectural and artistic values and traditions.
The inner world of the artificial rocks
A small section of the inside of the Great Rock was open to visitors for approximately 80 years. This was the Lion Cave, which by its rectangular solid shape hid the curiority of the rock space from the visitors. The audience was separated from the large cats by iron rails, the poor lighting, the obtrusive lion smell and the closeness of the predators as well as their at times spine chilling roars made the place legendary. The visitors could enter the most terrifying sanctuary of zoology through a cave-like gate from the bear areas on the northern side of the Great Rock, although many ventured no further than the doors. The most popular song regarding the zoo in the 1950s was born around this, the “Daddy, how does that large elephant enter the cave of the lion?”, which was sung by Tivadar Bilicsi.
A guide from 1913 described the circumstances as: “…we reach a gate leading into the side of the hill, on entering we come to the lion house. This was built under the empty hill in a way, that the audience can walk through it, its wide corridor running in front of the iron barred cages. Here the animals are in a dim place, which otherwise they like, as when living in the wild they spend their days hiding and only set off after their prey in the evening or early morning. We can see numerous lions in nine cages…Proceeding forward we reach the tigers…The long corridor of this house hidden inside the hill opens to the valley in front of the Tejcsarnok.” (Guide)
According to the Lendl concept they tried to display at least a few representations of all of the significant as well as interesting animal groups so visitors would be able to meet as wide a cross section of the animal kingdom as possible. With some of the animal groups however problems occurred. Solutions for keeping whales in a zoo have only been achieved in the case of some of the toothed whale species, until today there have been only two cases when Minke whales were kept in captivity for a short time. Lendl and his colleagues solved the problem as follows:
“The line of water mammals could be interestingly followed by the whales (that are wrongly called fish) that have almost taken fish form in their appearance, also by some species of dolphins; but these cannot be bred, at least not the whales as they are aquatic giants. Although the dolphins are smaller and are common in the Adriatic Sea, nobody has ever experimented with them in a zoo before. In order that they would also be included we agreed to the following plan. The entire large hill will be made of cement concrete and will be empty inside. We will open the wall on one of the sides with a cave like gate entrance enclosing it with a light structure, and in the inside a huge hall, this could even be 30 m long. We will erect a stuffed whale here from the northern seas, perhaps together with the skeleton, and also several specimens of dolphins, as these are not expensive and are very characteristic animals that can rarely be seen.” (Lendl)
They also wanted to house the museum for the specimen demonstration of animals that died in the Zoo in the cathedral sized centre of the Great Rock. Two years after the second opening of the Zoo in 1912, World War II broke out and the ideas developed regarding a “Zoological Museum”, due to the absence of appropriate resources, were removed from the agenda for almost a century. So between the two world wars the inner spaces of the Great Rock served as an ice rink and later a pony riding ménage, although most of it was used for hay and general storage. Sometimes of course special uses also occurred: the film “The Fort” was shot here in the beginning of the 1980s and in 1977 the “Numero Uno” avant-garde artist group organised a by and large illegal exhibition in the bear corridor. In the still “unfinished” rocky area in 2008 many successful concerts and events were held and from 2009 a 3D movie was set up in the domed hall.
The inside of the smaller of the rocky hills (Hill “B”, in today’s name “Small Rock”) was already formed at the time of construction: in it the latest amusement of the time, a “moving picture theatre” was created, which still operated in the 1980s. The glory of the Cave Cinema reached its zenith in the years of the 1960s, when nature documentaries, informative lectures and student competitions followed one another. During the reconstruction works of the Small Rock in 1997-98, not any less popular events, exhibition halls and fast food restaurants were developed in its place. The installations of the Small Rock provided several examples and lessons for the utilisation of the Great Rock.
The media of the time reported on the reopening of the Zoo in 1912, as the opening of one of the most modern zoos of Europe. The new taxonomic based division won great recognition together with the dry trench artificial rock display system, as well as the fresh water and marine aquariums that had not previously existed in Hungary. Its success was also shared amongst the architects and the industrial designers, with the specialised press at the time enthusing over it as an outstanding product of our national culture.
Changing animal runs at the side of the rock
The new animal housing developed during the complete renovation of the structure and run systems of the Great Rock between 2006 and 2008 equally meet the requirements of today as well as the needs for the preservation of traditions. The gorilla family of the Garden was given a new multiple sized accommodation, compared with the previous smaller facility, on the site of the former lion cave in the south-western side. The background for the run is provided by the rock itself and the shaded and hollow sections of the old lion cave offer pleasant resting places in the hot summer months. The gorillas’ garden is also enriched by a jungle gym and rest areas made of large oak logs and planks. In the neighbourhood of the gorilla enclosure on the southern side, the deepened run, which in the last century was populated mainly by chamois and goats, today is shared by maned sheep and Barbary monkeys.
Not far from here, in an area of over half a hectare, visitors are welcomed by a rather unusual picture. Giraffes pass with dignified steps in the shade of the giant rock. Sitatunga graze around them and gazelles drink at the rippling water of the small waterhole, the sentinel of a Meerkat group watches from a nearby peak the liberated galloping of a small rhinoceros calf. This view, of a community of animals normally seen in the African Savannah, is created in the largest run of the Zoo and only an arms length from the throbbing business quarter and pedestrianised streets of the inner city. In the zone displaying the wild fauna of African grasslands, in addition to the existing species of giraffes and rhinoceroses, visitors can also see animals that so far have never been shown in Hungary before. Such rarities for example are the large horned Sitatunga and the Mhorr-Gazelle, but in the run that is divided into several sections there are also Meerkats, vulturine guineafowls, giant turtles, mongooses, marabous, African geese and storks.
The new Savannah is not only a display of animals, but in compliance with today’s modern zoological approach, it is a complex live exhibition, where visitors also get a taste of the culture of the once “Dark Continent”. A few characteristic works of African folk art and traditional handcrafts are displayed as a separate exhibition in the visitor corridor of the stable building. Approximately eighty different artefacts, wooden statues, bronze figures from Ghana and even an entire collection of masks take the visitors to the land of Africa.
Bears had already lived in the Zoo back in 1866, in the year of it’s opening. The first bear cage was in use up to the beginning of the 20th century, then following the reconstruction between 1907 and 1912 the bears were accommodated in the new collective enclosure of the Great Rock. Originally two “bear lines” were created on the northern side. The “small bear line” was essentially made up of tiny neighbouring cages, which were closed down by the Zoo as unsuitable for animal housing, in the middle of the 90’s. The “large bear line” was made up of three rock runs, where, based on the Hagenbeck model, the animals were separated from the audience by a wide dry trench. These rock runs were in use until the beginning of the renovation works of the Great Rock. When creating the new bear enclosures, the three previous spaces were in essence opened up together, and by using the former trench and the upper walkway it was even extended. This way a large and spacious free run of 420 square meters was created in the side of the Great Rock. The size of the area made the construction of a large pool with a capacity of thirty thousand litres of water possible. During the renovation the original rock surface was naturally preserved, which is under monument protection. The run itself was developed in a way for the audience to be able to view and experiance the bears close up through a glass wall but still in safety. The completely reconstructed run has became a home for brown bears. A group of Asian wild dogs live in the run next to them.
The future of the Great Rock: a special exhibition space
Everyone admires the space increasing role of the amoeba like layout of the Great Rock. It still provides a believable scene and backdrop for the modernised animal enclosures. An excellent string of special pavilions had been built around it, which showed the characteristics of ’Arts and Crafts’, Transylvanian folk architecture, Secessionist and Romantic exotism. The house with the cupola (designed by Kornél Neuschloss) for Pachyderms was built as a counter point in the south-eastern side using Ottoman Islam, Persian and Indian architectural styles. The exotic neighbour of this at the side of the Great Rock was the Giraffe house, showing a north African Arabic influence and with two Transylvanian beamed pavilions next to it. Then came the Buffalo and the deer houses with the Központi Tejcsarnok (Central Dairy) that was built at the foot of the rock, following the original style. The south-western side was bordered by the triumvirate of the Monkey, the Rodent (now used by mandrills) and the Kangaroo houses (nowadays it is referred to as Bambi House and inhabited by lemurs), and from north-west by the large predator house. All of these were designed by the Kós-Zrumeczky architect genius pair.
Unfortunately the harmonious overall picture was soon disturbed, first in 1915 when the tower of the Pachyderm house was demolished and later, when such buildings which survived World War II fell to the modernisation fever of the 1960-70-80s. The new Giraffe House and the Buffalo House were rebuilt this way in the manner of the panel era and exactly in place of the originals. The Tejcsarnok was transformed into a rectangle block and the Deer House was placed at the other end of the Garden with the architecturally insignificant and exaggerated sized House of the Anthropoids built in its place in 1988.
Between 2006 and 2008 the complete renovation of the rock surface as well as of the Tejcsarnok was completed, which was just in time, as the inner spaces had been declared unsafe for decades. As they were primarily used for storage, workers were protected from concrete pieces breaking off the inner shell of the rock, which randomly fell in sizes of half to ten kilograms, by stretched steel nets! With the completion of the renovation of the crust the fulfilment of a century old dream became possible, namely the development and furnishing of the inner space of the Rock. This was also included in the reconstruction programme, however due to lack of finances it did not take place in 2008.
By the utilisation of the inside of the Rock, the Zoo that has been struggling with a small site, will gain several thousand square meters of new exhibition area and a worthy area for cultural programmes, events and conferences. The special circumstances, e.g. the spatial structure with its unusual ambiance and absence of natural light, require the installation of special functions or the positioning of a dedicated structure. In addition to the construction of the inner side of the Great Rock, plans have also been drawn up to have the majority of the former high standard buildings in the vicinity renovated. The architectural programmes for the reconstruction of the Buffalo and Giraffe Houses were made based on the former designs of Kós and Zrumetzky and the rebirth of the buildings could take place in the coming years.
The creation and furnishing of the inner space of the Great Rock into an exhibition space, the century old dream of Adolf Lendl can finally become a reality. The designs for the exhibitions planned here have been completed; the audience will meet specialities of the living world and “magical rarities” within it. A unique and spectacular display of the extraordinary life forms ever appearing on Earth’s stage and of the development of life and its amazing richness could be exhibited here. A well equipped special exhibition system will be created with interactive and adventurous games, demonstrations of live animals and models of giant animals together with opportunities to get to know the microscopic world. With all these possibilities for synergistic discovery, lecture theatres as well as modern exhibition technology equipment with no other like it, it will be unmatched in Central-Europe.
The shaping of the inner spaces and designing the lighting of the structure imitating a limestone hill is based on the examination of caves. As water finds its way in a giant limestone block, light finds its way in the huge dark and empty spaces of the artificial rock bounded by a thin crust. The internal view can also be enjoyed from the heated spaces installed in many places in a transparent way as an “orangery”. It is as if the special play and atmosphere of the inner spaces and light conditions would evoke a magical landscape on a night with a full moon, a “night garden” full of life forms in the imaginations of the visitors.
Péter Kis, Miklós Persányi, Márta Szabon
Budapest Székesfővárosi Állatkert útmutatója, Magyar Földrajzi Intézet (Guide of the Budapest Capital Town Zoo, Geological Institute of Hungary), Budapest, 1912. (Útmutató)
Dr Lendl Adolf: Milyen lesz az új állatkertünk? (What is our new Zoo to be like?) Fővárosi Közlöny (The official Journal of the Council of Budapest) Issue 6/1909
Magyar Építőművészet (Hungarian Architectural Art), 1912. Issue 11-12: A Budapest székesfővárosi állatkert (Budapest Capital Town Zoo), 1912
Michailich Gy.-Haviár Gy.: A vasbeton építés kezdete és első létesítményei Magyarországon (The beginnings of building with reinforced concrete and its first establishments in Hungary) Akadémiai Kiadó Budapest 1966
J. Schumaus: Die künstlichen Berge des hauptstadtischen Tiergartens in Budapest Beton und Eisen 1912. Issue 8-9
Szidnainé Dr. Csete Ágnes: A 125 éves Budapesti Állat- és Növénykert története (The history of the 125 years of Budapest Zoo)
ÉMI T-7/ 1996 sz. szakértői vélemény (expert opinion)