The first and most famous of the Unités d'Habitation buildings, also known as La Cité Radieuse (The Radiant City) and informally as La Maison du Fada (French – Provençal, "The Madman's House"), is in Marseille, France, and was built from 1947 to 1952. One of Le Corbusier's most famous works, it proved enormously influential and is often cited as the initial inspiration for the Brutalist architectural style and philosophy.

The building is constructed in béton brut (rough-cast concrete), as the hoped-for steel frame proved too expensive due to the post-war steel shortage. In July 2016, the Unité in Marseille and several other works by Le Corbusier were designated UNESCO World Heritage Sites. It is also designated an historic monument by the French Ministry of Culture. It was damaged by fire on February 9, 2012.

The Marseille building, developed with Le Corbusier's designers Shadrach Woods and George Candilis, comprises 337 apartments of 23 different layouts, over twelve stories, all suspended on large pilotis. The building also incorporates shops including an architectural bookshop, a rooftop gallery, educational facilities, an hotel that is open to the public, and a restaurant, "Le Ventre de l'Architecte" ("The Belly of the Architect").

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.

The flat roof is designed as a communal terrace with sculptural ventilation stacks, a running track, and a shallow paddling pool for children. There is also a children's art school in the atelier. The roof, where a number of theatrical performances have taken place, was renovated in 2010, and since 2013 it has hosted an exhibition center called the MaMo. The roof has unobstructed views of the Mediterranean and Marseille.

According to Peter Blake, members of CIAM held a "great celebration" for the building's opening on its roof, on a summer evening in 1953. "Architects from every part of the world attended", including Walter Gropius, who said at the event: "Any architect who does not find this building beautiful, had better lay down his pencil."

source: Wikipedia