San Agustín, on Calle Bolívar at the corner of Calle San Alberto, is a 17th-century Augustinian church best identified from a distance by its single tall bell tower, the highest in the historic centre. The church's plain stone exterior masks an unusually rich interior — gilded baroque altarpieces along both side walls, a finely carved pulpit, and a 18th-century image of San Agustín wearing a real bishop's mitre.
The Augustinian cloister beside the church has been partially restored and houses a small museum of religious art. Hours are erratic but the church itself is usually open for mass and a quick visit in the late afternoon. The tower can sometimes be climbed for a small fee and the view is one of the best in the city, level with the cathedral spire.