The idea came from the numerous abandoned building sites in Sofia. We suggested a building a two stages, that gradually reveals in time changing its function until it reaches its full capacity. It has an initial and final state but it could be properly used a any of its intermediate stages. The final state is the completed office building. The first stage is the smallest possible investment to make the building function. At this stage it consists of several open sports playgrounds placed on top of each
other. They share an open staircase which could be used later as an emergency exit from the offices. Each playground is at least three floors high so at this stage only 10 out of 18 slabs are needed. The changing building is sensitive to the local necessities offering various functions at different times. During its intermediate stages it presents a puzzle of closed private office spaces and open public sports playgrounds.