In a plot of 411m2 in Chalandri the owners requested two independed houses, arranged on three floors. The first house occupies the ground and the first floor, while the second the last floor. The two houses have separate entrances and the last floor house is approached through an open air staircase or by an elevator. Utilities and a car parking are placed in the basement. As the climate in Athens is Mediterranean – mild it is a custom, during many months of the year, daily activities to be held outdoors. Therefore it is essential in the design process to incorporate agreeable open air living spaces. In this case a box of in situ exposed concrete encloses the L shaped building volume and an open air courtyard. Most internal spaces face into the courtyard which includes a pool. The idea of a house with an enclosed open air space is quite old and commonly used in many parts of the world, as it serves well urban habitation. In this case, the outdoor living space is clearly defined by sharp borders – full height walls that provide regulated climate conditions (shading – protection from strong winds) and privacy as well as a controlled visual relationship with the surroundings.