Structure 17, which we name Las Gemelas, is located to the west of the South Plaza and is the one that presents the best-preserved architectural features of Ek Balam. It is made up of a large base on which two or more were built to support two vaulted buildings, each with four rooms. The structure is 40 meters long, 17 meters wide and has an approximate height of 6 meters.
The decoration of the facades in the buildings of Ek Balam was not done with figures carved in the stones - as in Uxmal and Chichen Itzá, for example - but with stucco or lime mortar, modeled in different shapes and painted.
During the excavation, two stucco masks were found that were part of the ornamentation. In this building, the only decorative stone elements are the small rings that are in the corners of the rooms.
Under the building that we can now admire there are two structures that were completely covered: it was the custom of ancient Mayan architects to use structures from earlier times as foundations for the construction of new buildings.