This 16th-century church, part of a strict convent, is difficult to visit but it's worth making the effort to go for morning services, because this is one of the more bizarre churches in Cuzco. Mirrors cover almost the entire interior; apparently, the colonial clergy used them to entice curious indigenous peoples into the church for worship.
The nuns provide the choir during Mass, sitting at the very back of the church and separated from both the priest and the rest of the congregation by an ominous grille of heavy metal bars stretching from floor to ceiling.