Inside, wide corridors ("streets in the sky") run along the central long axis of every third floor of the building. Each apartment lies on two levels, such that the room on one side of a corridor belongs to the apartment that is mostly below the corridor floor, while that on the opposite side belongs to the apartment above. On those floors without corridors, the apartments stretch from one side of the building to the other, and each has a balcony on the western side. Le Corbusier's design was criticised by US architect Peter Blake for having small children's rooms, some without windows. Unlike many of the inferior system-built blocks it inspired, which lack the original's generous proportions, communal facilities and parkland setting, the Unité is popular with its residents and is now mainly occupied by upper middle-class professionals.