Forte de São Diogo, Portuguese fortress in Barra, Salvador, Brazil.

Forte de São Diogo is a stone fortress located on a peninsula in Barra that overlooks the Bay of All Saints. The thick walls surround several structures inside, including gallery spaces and exhibition areas.

Construction began under governor-general Diogo de Meneses Siqueira (1609–1613) to a plan by chief engineer Francisco de Frias da Mesquita, and the site appears as Estância de São Diogo in João Teixeira Albernaz's 1616 map of Salvador. Rebuilt from 1626 under Diogo Luís de Oliveira, it withstood Maurício de Nassau's attack of April–May 1638 while still unfinished. Works from 1704 gave it its present outline, and it was reopened in September 1722 with a battery of seven guns.

The fort is named after Diogo de Meneses Siqueira, governor-general of Brazil from 1609 to 1613, under whose administration construction began. Today it serves as a cultural centre with a regular programme of events, and its garrison wears the historical uniform of the 1st Infantry Regiment of Bahia, part of a revitalisation project run by the state culture and tourism secretariat with the Brazilian Army.

The site is located in Barra and is easily accessible from downtown, allowing you to explore at your own pace. The paths on the grounds are relatively flat with shaded areas along the walls.

The fort appears on a 1998 Telebahia phone card in its Fortes de Salvador series, showing the facade and entrance. Its garrison wears the historic uniform of the 1st Infantry Regiment of Bahia, part of a revitalization project by the Culture and Tourism Secretariat with the Brazilian Army.