Fuerte de Braganza, Colonial fortress in Costa Marques, Brazil

Forte de Bragança stood on the right bank of the Guaporé River, about two kilometres downstream from the present Real Forte Príncipe da Beira, in what is now Costa Marques, Rondônia. Rebuilt from 26 September 1767, it had a Vauban-style bastioned plan measuring 40 braças (88 m) across the front and 20 braças (44 m) deep. It was renamed Forte de Bragança in 1769 by governor Luís Pinto de Sousa Coutinho.

The site began in 1753 as the Guarda de Santa Rosa, a watch post set up by governor Antônio Rolim de Moura Tavares after he dislodged a Spanish reduction on the Guaporé's right bank. Rebuilt as the Presídio de Nossa Senhora da Conceição with a pentagonal plan, it was attacked by Spanish forces in April 1762. Reconstructed from 26 September 1767, it was renamed Forte de Bragança in 1769 by governor Luís Pinto de Sousa Coutinho; ruinous again, it was replaced from 1776 by the Real Forte Príncipe da Beira.

The fort's name changed with its governors: built as the Presídio de Nossa Senhora da Conceição, it was renamed Forte de Bragança in 1769 by governor Luís Pinto de Sousa Coutinho. Its earth-and-fascine ramparts, rebuilt from 26 September 1767, followed the Vauban bastion system, with a main body about 88 m wide and 44 m deep.

The fort stood on the right bank of the Guaporé, about two kilometres downstream from the Real Forte Príncipe da Beira, in what is now Costa Marques. The site itself is gone: by 1958 a landing strip called Fazenda Conceição occupied the spot where the Forte da Conceição had stood. Plan to look for the location rather than standing walls.

The fort was rebuilt from 26 September 1767 after ruin, and in 1769 governor Luís Pinto de Sousa Coutinho renamed it Forte de Bragança. Its earlier name honoured Nossa Senhora da Conceição. Constant flooding later led Luís de Albuquerque de Melo Pereira e Cáceres to replace it from 1776 with the Real Forte Príncipe da Beira, about two kilometres upstream.