It was used by missionaries responsible for evangelizing the Sierra Gorda, either to treat their illnesses or to learn the indigenous languages of the region.

From the western side of the atrium, one can observe the temple and the Chapel of the Third Order, while the southern side features the portals that provide access to the convent.

The convent has two floors with spacious corridors and a sacristy on the ground level. Like many other religious buildings, it was looted and converted into a military barracks following the Reform Laws until 1884 when the temple was rededicated.

The Chapel of the Third Order is annexed to the church, dating back to 1740 and dedicated to Saint Rose of Lima.

The temple's façade is a very austere Baroque style made of quarry stone. It consists of two levels, with Corinthian pilasters and large pedestals on the first level, including the main arched entrance. The second level features a sculpture of Christ on the cross, with a pediment and a central coral window. The rest of the wall displays three shields representing the orders of the Mercedarians, Franciscans, and Dominicans.

The church is built in the shape of a Latin cross and has a tall tower with three square levels.