The Nunnery complex is the largest structure in what is called the Late Classic zone (600-950 A.D.), which preceded the Toltec takeover of Chichen Itza. However it also shows some influence of later residence. The building itself is of the Chenes style, which is a local Yucatan style. The main part of the Nunnery consists of a series of vaulted rooms seated on a 33 foot (10 meter) high platform mound. Some of the rooms were abundantly decorated with mural paintings and stone mosaics in the late Puuc style. The doorway lintels have well-preserved carved hieroglyphs referring events that took place around 880 A.D. Later on, another small construction was added as a third floor, completely built in the Maya-Toltec style, for which many Puuc decorated pieces were reused.
A jaguar throne and a stone altar used for human sacrifice was found in front of the building. The name of the Nunnery (Las Monjas in Spanish) comes from the erroneous interpretation of the first Spanish visitors who, upon seeing the large number of rooms, were reminded of the cells of a monastery. Most archaeologists now believe it was a palace for Maya royalty.