Located some 80km downriver from Corumbá along Rio Paraguai, this large fort was built in 1775 to repel invaders from Paraguay, which it failed to do quite spectacularly in 1864, when it was overrun by the Paraguayan army. As the fort is on Brazilian army territory, tour agencies have to obtain permission to visit. Tours are done either by boat – a spectacular journey that passes by two impressive caves – or by driving to Porto Morrinho and then continuing by boat.
Expect to pay around R$400 including lunch for a tour. The military base in Corumbá can give you further information on visiting the fort.