The Cathedral da Sé is the seat of the Archdiocese of Mariana, established in 1745 as the oldest diocese in Brazil. The interior is an accumulated history of colonial patronage: gilded altarpieces, carved woodwork, and painted ceilings accumulated across two centuries of Church wealth from the surrounding gold-mining region. The most remarkable piece is the 1701 German pipe organ, brought from Portugal and installed when Mariana was still a raw frontier city.
Admission is free, though the attached Museu Arquidiocesano, housed in the bishop's palace next door, charges a small fee and holds one of the best collections of sacred art in the state — colonial paintings, processional silverware, and wooden polychrome sculptures spanning the seventeenth and eighteenth centuries. Allow at least an hour for both.