At the end of 1998, the Mautner-Markhof Children's Hospital in the 3rd district of Vienna was closed. In 1999 the municipality explored alternative development possibilities for the vacant area. A limited design competition was held, from which Coop Himmelb(l)au emerged as the winner. The architects suggested to conserve to a large extent the valuable trees existing along the Kleingasse and set two slim building volumes in line with the street Slachthausgasse in order to return the urban block into it's previously defined form. The complex now contains 82 apartments and approximately 12000 m2 of office space. The 6+1-storey building is individually differentiated by sculpturally protruding building components. In the so-called 'Head Building' oriented toward the south, a youth centre with own meeting spaces is the basement is integrated (text from website architects).