The Prioral Church of Santa María de la Asunción sits at the heart of the old town, built on the site of the main mosque after the Christian reconquest of 1247. The cloister, which predates the church, was constructed around the ablutions courtyard of the original mosque — you can still see the Moorish horseshoe arches around its perimeter. A Visigothic calendar carved in stone is embedded into one of the walls and is one of the more unusual objects in the building.
The church was built in the late Gothic style over the 15th and 16th centuries and is Carmona's main parish church. The interior is large and cool, with a wide nave, good 16th-century altarpieces, and an organ case worth noting. It is generally open to visitors in the mornings; check at the tourist office for current hours.