Well worth visiting. Stay for coffee or drinks.
Fort Copacabana is a military base at the south end of the beach that defines the district of Copacabana, Rio de Janeiro. The base is open to the public and contains the Museu Histórico do Exército (Museum of the History of the Army) and a coastal defense fort that is the actual Fort Copacabana.
… At the entrance to the base there is a guard in the uniform that was current when the fort was opened in 1914.
The museum is only in Portuguese. Up top on Canon’s Dome was my favourite part.