Casa Fiat de Cultura is one of the more ambitious exhibition spaces on Praça da Liberdade, run by the carmaker Fiat in a restored mansion the company bought for the purpose. The schedule leans toward big international touring exhibitions — Picasso retrospectives, Warhol shows, surveys of Brazilian modernism — that are unusually well presented for a corporate-funded space.
Admission is normally free or very cheap, and the building includes a good cafe in the courtyard at the back. Worth checking what is on when you are in the city.