The Letter of Athens is a fundamental document in the history of 20th century urban planning that includes the conclusions of the IV International Congress of Modern Architecture (CIAM) in 1933. Published around 1942 in a version edited by Le Corbusier, it constitutes one of the most influential manifestos of functionalist urbanism and modern planning. The text proposes a comprehensive reorganization of the city based on hygiene criteria, functional rationalization and zoning, and significantly influenced post-war urban strategies.[1]​.

During the 1920s and 1930s, European industrial cities faced serious problems related to density, unhealthiness, and lack of adequate housing. In this context, CIAM emerged, founded in 1928 with the aim of developing a modern theory of architecture and urban planning.[1]​.

The IV Congress, held aboard the ship Patris II, brought together delegates from different countries who systematically analyzed the urban situation of several European cities. These investigations included data on density, housing, mobility and public space. The conclusions were intended to form a common text that should guide the rational planning of the modern city.[1]​.

The Athens Charter has requested in matters of habitation:

The Athens Charter supports a functional separation of places of residence, leisure and work, calling into question the character and density of the traditional city. This treaty proposes the placement of buildings in large, sparse green areas. The articles of the Charter are accompanied by explanations written by Le Corbusier and by Jeanne de Villeneuve"), Baroness d'Aubigny.[2]​.

These precepts had a great influence on the development of European cities after the Second World War and on the design of Brasilia.

The original ideas of the Athens Charter are strongly influenced by Cornelis van Esteren's exhibition "The Idea of ​​the Functional City" of 1928.

The manifesto has been widely criticized for the simplification of some of its contents.