Giuseppe Terragni was twenty-eight when he received the commission, and the building he produced is barely four storeys high. Yet within those modest dimensions he compressed an entire architectural argument. The plan is a square, 33.20 metres on each side; the height is 16.60 metres, exactly half the width. The result is a half-cube, a volume whose proportions can be read at a glance and never resolved into anything fussier. Where earlier party buildings reached for towers and balconies for the orator, Terragni gave Como a calm, transparent block faced in pale Botticino marble.

The transparency was the point. At the centre of the building Terragni placed the Salone delle Adunate, a double-height assembly hall lit from above through a roof of concrete-framed glass blocks. The main facade on Piazza del Popolo opens into a loggia of five spans, and the original sixteen glazed doors could be thrown open at once so that a crowd in the square and the party members inside became, for the length of a rally, a single continuous space. Terragni described the building in almost mystical terms — fascismo è una casa di vetro, fascism as a house of glass — an architecture of total visibility serving a politics that was anything but.

That contradiction is exactly why the building still rewards a visit. Terragni died in 1943, and the regime he built for collapsed two years later; the Casa del Fascio passed to the Guardia di Finanza, which occupies it still. Stripped of the bas-reliefs and slogans once planned for its walls, the structure reads now as what it always also was: a lesson in how proportion, daylight and a few honest materials can hold a public square. It was listed as cultural heritage of major historical and artistic interest in 1986, and remains the obligatory first stop on any tour of Como’s extraordinary concentration of Rationalist architecture.