ne of the more notable and largest structures at Chichén Itzá is a complex of terminal classic buildings constructed in the Puuc architectural style. The Spanish nick-named this complex “Las Monjas”, although it was actually a governmental palace.
The main building of this complex is the so-called "Nunnery" or "Platform 5", whose platform is 50 m long and 28 m wide. In front of it is a 17m wide main stair, leading to a superstructure with numerous chambers and detailed wall-decoration.
The East Wing is located immediately adjacent to the Nunnery and while it is from the early Mayan period of Chichén Itzá, it shows some influence of later residence. This building is of the Chenes style, which is a local Yucatan style. It has a lattice motif on the roof comb, complete with Chac masks, but it also includes an undulating serpent running along its cornice. The decoration begins at the base and goes up to the cornice, with the façade completely covered with several rain god masks with a central richly clad human figure over the doorway. A hieroglyphic inscription is on the lintel.
Another structure was named La Iglesia (the Church) by the Spanish, probably because it was located right next to the Nunnery. This rectangular building is of classic Puuc construction with an overlay of central Yucatan styles (Chenes). This is probably one of the most frequently drawn and photographed buildings at Chichén Itzá; famous 19th century drawings were made by both Frederick Catherwood and Desiré Charnay. The Iglesia is rectangular with a single room inside and an entrance on the west side. The outside wall is completely covered with veneer decorations, which extend clear up to the roof comb. The frieze is bounded at ground level by a stepped fret motif and above by a serpent; the stepped fret motif is repeated on the bottom of the roof comb. The most important motif of the decoration is the Chac god mask with a hooked nose standing out on the corners of the building. In addition, there are four figures in pairs between the masks including an armadillo, a snail, a turtle, and a crab, the four "bacabs" who hold up the sky in Mayan mythology.
Another building is the South Annex, which also is decorated by 3 Chac Masks and can be seen as a typical representation of the Puuc style.