The Catedral de Santo Antônio stands on the main square and is the most prominent building in Diamantina's historic centre. The current structure dates largely from a 20th-century rebuild, but the interior retains its ornate 18th-century altarpiece and carved wooden choir stalls, both survivors from the original church funded by the town's diamond trade wealth.
The interior is dark and cool, and the scale of the carved gold-leafed altarpiece — crowded with saints, cherubs, and decorative foliage — says everything you need to know about how seriously the diamond contractors took their devotion. The church is open most mornings and free to enter.