The Monastery of San Antonio de Padua, in Izamal, Mexico, was completed in 1561. Its atrium was then the second largest in the world, after the Vatican's. The Franciscan Bishop in charge, Fray Diego de Landa, was in charge of the inquisition, and is responsible for burning thousands of ancient Maya priests and codices - a cultural catastrophe. Ironically, the monastery is built atop an acropolis (in green) which supported the largest temple in the ancient Maya city located there, which stones were re-used in the construction of the monastery.
Today, you can visit both the monastery (which is beautiful) as well as five pyramids which still stand within this gorgeous colonial town of Northern Yucatan.