La Cité Radieuse, Marseille (must see)

The first and most renowned among the Housing Unit (Unités d'Habitation) buildings is situated in Marseille. Commonly known as The Radiant City (La Cité Radieuse) and informally referred to as La Maison du Fada (French – Provençal, "The Madman's House"), it was constructed from 1947 to 1952.

This iconic work by Le Corbusier has had a profound impact on architecture, often considered the initial inspiration for the Brutalist style and philosophy. The building's construction primarily utilizes béton brut (rough-cast concrete) due to the post-war steel shortage, as the intended steel frame turned out to be too expensive.

Le Corbusier collaborated with designers Shadrach Woods and George Candilis to develop the Marseille building. It boasts 337 apartments with 23 diverse layouts, spread across twelve stories, all supported by large pilotis. In addition to housing, the building includes various amenities such as shops, an architectural bookshop, a rooftop gallery, educational facilities, a public hotel, and the restaurant "Le Ventre de l'Architecte" ("The Belly of the Architect").

Inside the building, wide corridors are designed as "streets in the sky" running along the central long axis of every third floor. Each apartment spans two levels, with rooms on one side of the corridor belonging to the apartment below it, and those on the opposite side to the apartment above. Apartments on floors without corridors stretch from one side of the building to the other, each featuring a balcony on the western side.

The flat roof of the building is ingeniously designed as a communal terrace, featuring sculptural ventilation stacks, a running track, and a shallow paddling pool for children. Moreover, an atelier hosts a children's art school. Renovated in 2010, the roof has become a venue for various theatrical performances and, since 2013, has served as an exhibition center called the MaMo. Its unobstructed views of the Mediterranean and Marseille make it a remarkable space.

In recognition of its architectural significance, the Housing Unit in Marseille, along with other works by Le Corbusier, was designated as a UNESCO World Heritage Site in July 2016.