The palace of Peter 1 and Peter 2nd, the first Portuguese rulers in Brazil. It's not a very ornate palace but was the only building big enough in the city to be able to house the royal entourage when they moved here from Portugal. The area outside is used as a public market on weekends.
The Municipal Theater, with new green and gold highlights on the roof. It's quite beautiful, really.
Such a variety made it very interesting.