San Pedro Apóstol was built by Jesuits in the sixteenth century over a pre-Columbian huaca, or ceremonial space. Much of the interior was decorated by Luis de Riaño, a student of Angelino Medoro, in the 1620s. It is often called the "Sistine Chapel of the Andes" because of the beauty of its mural paintings. The sanctuary has a polychrome ceiling in the Mudéjar style built using a pre-Hispanic construction method called kur-kur, which combines cane, straw, and mud instead of wood.The immense Plaza de Armas is surrounded by leafy pisonay trees (or coral trees) and palm trees. It is considered one of the most beautiful squares in the region