Xlapak is a very small site that is very close to Labná -- so close, in fact, that it may have actually been part of Labná. Structure 1 is the only building on the site that is in good enough condition to be of interest to anyone but an archaeologist. It is an interesting example of the Classic Puuc Mosaic Style and dates to approximately A.D. 830 to 1000. According to Joyce Kelly, Structure 1 was restored by the Mexican government in the late 1960s.
"There are sets of Chac masks in stacks of three on the corners of the upper facade and above the center doorways on the north and south sides. The masks rise above the coping course, which gives them special emphasis."
Joyce Kelly, An Archaeological Guide to Mexico's Yucatán Peninsula, p. 132
"Northern range aparently conceived by builders after walls, and possibly vaults, of central and southern ranges had been built. Old north wall then thickened, in accordance with custom of making interior walls heavier than outer in order to carry weight of two vaults, and northern range built. Balanced design of decoration on east facade suggests facing of upper facade not applied until all vaults had been constructed, but may have been dismantling and rebuilding."
H.E.D. Pollock, The Puuc: An Architectural Survey of the Hill Country of Yucatan and Northern Campeche, Mexico, p. 64
"Alternating between the simple and the sophisticated, the "Chac" masks enliven some of the most brilliant architectonic creations of this flourishing phase. A good example of the process of simplification, of extreme "geometrization," which many of these masks underwent then, can be seen on the Palace at Xlapak, where they adorn large ornamental panels that highlight the roof level both at the corners and over the central doors."
Paul Gendrop, Rio Bec, Chenes, and Puuc Styles in Maya Architecture, p. 180-1
The pattern between the mask panels at Xlapak is identical to the decoration on the east side of the great Portal Arch at Labná.
The south side of Structure 1 was apparently built slightly earlier than the north side. A small chultun (cistern for collecting and storing water) can be seen in front of the building.