The building ensemble consists of 3 parts surrounding a courtyard. The new extension was built from 2005 till 2006 and created a new entrance to the whole ensemble. The new building has 3600m2 of gross floor space. A huge amount of the new built space (2000m2) is underground used for archives. The public facilities are located on the ground floor close to the entrance. The library connects the ground- and the underground floors. The first and second floor contain mainly offices and guest apartments. The guest apartments have a separate entrance. The third floor is the conference area. The new building fits into the ensemble by using the same façade material already existing in the older buildings. Cooper is the favourite choice. Having a similar surface and a modern shape the new extension the new address of the ensemble.