A small chapel inside the Franciscan convent complex of Santo Antônio do Convento, and the most spectacular interior in the historic centre. Every surface is carved and gilded woodwork from the late 17th century: pulpits, tribunes, the main altar, the ceiling, even the side panels.
Entry is through the Museu Franciscano de Arte Sacra, which is worth a look in its own right for religious painting and sculpture. The visit takes about an hour. Closed Sundays.