If you stand on the colonnade on top of the North Platform, it is possible to see to internal area of the sunken Patio,or Patio Hundido. This is a squared plaza, about 160 feet across, and was excavated about 13 feet below ground level. It is accessible through stairs on each side and in the middle stands a squared altar.
The interior of the sunken patio is visible only if you stands on its edges, and for this reason, it has been suggested that it was an area where Monte Albán elites carried out private ceremonies, offerings and sacrifices. The patio is surrounded by temples, like Building B, A, and I. Building I and the central altar of teh sunken patio is where, in the 1930s, the Mexican archaeologist Alfonso Caso encountered some of the Teotihuacan-style artifacts.