The east side of the main plaza is marked by several imposing buildings, among which is the so-called Palace, or Building S.
Building S is a rectangular precinct, built above a platform, closed on all sides and accessible only through a doorway covered by a stone lintel. Inside there are several rooms disposed around a central patio. Some of the lateral rooms have stone benches probably used as beds. Behind the main entrance the interior of the house is closed from sight by a wall.
The squared structures measures about 80 ft per side. the central patio is occupied by a small altar probably used by the family for private rituals and ceremonies. This residence represents the typical characteristics of Zapotec palace architecture. Usually family tombs were located under the internal patio and were periodically accessed by the descendents of the dead.