This structure combines an early (Monte Albán I) building, which contained famous carvings known as Danzantes (Dancers), with a later structure that was built over it. There are a few original Danzantes in a short passage which you can enter, and copies of others along the wall outside. Carved between 500 and 100 BC, they depict naked men, thought to be sacrificed leaders of conquered neighboring towns.
The Danzantes generally have thick-lipped open mouths (sometimes down-turned in Olmec style) and closed eyes. Some have blood flowing where they have been disemboweled.