The mixed-use complex 'The Circle' at Zurich airport, hosting a range of activities and services under one roof, is the biggest Swiss building construction project in recent years covering 180,000 sqm (1.9 million sq ft) of usable space. The building’s acoustic windows and sustainable closed cavity façade allow to create a city without noise which follows the ring shape of the motorway and covers parts of the road. Squares and lanes aiming to echo the flair of the city center of Zurich are covered by an air permeable glass roof thus generating rain protected outdoor ambiences. Within walking distance to the terminals, the architecturally striking building complex is being developed allowing for a variety of uses, services, and interactions and creating the atmosphere of an international trading center. Despite the high compactness, Riken Yamamoto, architect of the building complex, grouped the six buildings in a way as to reduce large building areas gradually towards the hill which gives the impression of a small scale city center. The single buildings are 9 to 11 stories high and the maximum building height amounts to 38 m (125 ft). The development is LEED Platinum^® and it is the largest building ever certified by Minergie, a Swiss construction standard for new builds and renovated buildings.