This book outlines the main features of the social housing districts built in Milan since 1903 when the Istituto Autonomo Case Popolari was tasked of making subsidized houses for low income people. The standpoint concerns both the urban and architectural design: the development of social housing affected the shape of the city, but in the meantime most of the modernist architects, who coped with the issue of social housing, did an effort to convey their experience as professional so that the house could turn into the home for everybody. Nowadays the subsidized districts can be considered as a wide «metropolitan-scale museum» in which the identity of large part of modernist architectural culture is stored up.