The Museu Histórico Nacional occupies a sprawling colonial fortification near Praça XV in Centro, including the old gunpowder magazine, the old arsenal, and the historic Casa do Trem barracks. It is Brazil's largest history museum, with over 350,000 items covering the full sweep of Brazilian history from pre-colonial times through the Empire, the Republic, and into the 20th century.
The collection includes colonial furniture and silverware, carriages from the imperial period, weapons, costumes, portraits of emperors and statesmen, and artefacts from the abolition of slavery in 1888. The building complex itself is part of the exhibit — the old fort walls and cannon emplacements are still intact. Less visited than the glamour museums of the Zona Sul, but more substantive for anyone interested in how Brazil actually got here.