Le Corbusier’s concept for a garden on the roof of a building was the roof garden.
The roof garden was the second of his Five Points of Architecture, a set of principles developed during the 1920s and published in manifesto form in 1927. Reinforced-concrete construction made flat roofs practical, and Le Corbusier argued that the roof should be reclaimed for domestic or communal use rather than left unused.
The idea also had an environmental rationale: a roof garden could replace some of the green space occupied by the building and help moderate the roof’s temperature and humidity. In practice, the feature could take the form of a planted garden, terrace, promenade, sports area, or even a swimming pool.
Readers sometimes confuse “roof garden” with “roof terrace.” They are closely related, but the canonical name of the architectural point is generally given as the roof garden. Villa Savoye, completed in 1928–1931, famously incorporated a roof terrace and garden as part of its architectural promenade.