Casa Rustici was designed in 1933 and built between 1934 and 1935 by Giuseppe Terragni, the Como architect best known for the Casa del Fascio, and Pietro Lingeri, his frequent Milanese collaborator. Their client, the engineer Vittorio Rustici, had first asked for a two-storey villa on the Corso Sempione plot and only switched the brief to a rental apartment building for economic reasons. The site is a corner lot where the boulevard meets the former Ferrovia Nord railway alignment, today Via Mussi; the irregular geometry pushed the architects to organise the programme into two distinct masses, one rectangular to the south, the other T-shaped to the north, separated by an open courtyard rather than welded into a single block.

The decision to keep the two volumes apart was both formal and theoretical. Terragni and Lingeri had been among the protagonists of the Movimento Italiano per l’Architettura Razionale (MIAR), the loose front through which Gruppo 7 and its allies argued, from 1928 on, for an Italian modernism that owed nothing to Beaux-Arts decorum or to the heavy Novecento revival. Splitting the volume let them treat each apartment as a thin slab that received light on both long sides, and gave the elevation a horizontal reading of cantilevered balconies, ribbon openings and pale stuccoed wall planes. The famous suspended walkways — balconate sospese in Italian — cross the courtyard at every upper level, tying the two blocks together while leaving the ground open to air and view.

The Milanese municipal commission did not share the architects’ enthusiasm. According to the published project history the design was rejected nine times before construction could begin, with objections concentrated on the unusual relationship between built volume and lot. When the building was finally completed in 1935 it gave Rustici six floors of rental apartments above a semi-basement of garages and offices, with a recessed penthouse villa for the owner himself on the roof — a private house, divided into two sections joined by a covered suspended passage, set back from the street line and almost invisible from below. Casa Rustici has been listed as protected heritage since 1988 and remains residential, which is part of its quiet authority: among the surviving monuments of pre-war Italian modernism, it is one of the few that never stopped doing what it was built to do.