It got its name from the Spaniards thinking that it resembled a convent. There are four long buildings surrounding a courtyard of 260'x218'. There are 74 rooms for students, priest or soldiers. They aren't sure, but may be administrative. Built around 900-1000 with a rich combination of decorative motifs such as lattices, columns, huts, Chaac masks, snakes, owls, Venus symbols and human figures.A two headed feathered serpent coils through the whole frieze. The close up photo shows its tail and a human looking out of the mouth. Also there is an old depiction included.