Monte Albán was founded around 500 B.C. and at its peak, it had about 35,000 inhabitants. Today, the archaeological site preserves a sacerdotal temple, a ballgame court, observatory, palace, several truncated pyramids, 170 elaborate tombs, and something more peculiar: hundreds of petroglyphs that are hidden among the stones.

The most notorious of these petroglyphs are found in the Plaza de los Danzantes. These are a set of stelae depicting naked and rather robust men partaking in what archaeologists think is some ritual dance, hence the name of the square (Plaza of the Dancers). The most recent interpretation of the images is that each figure may represent an enemy ruler that was captured and ritually sacrificed through being flayed alive, and hence some appear with ritual castration.

In other places, it's possible to see hieroglyphs that correspond to the calendar. One stele is even aligned with the polar star facing north. And on the sides of one of the pyramids (Building J), there's a series of images that show the cities conquered by the army of Monte Albán.

One of the earliest and most important Mesoamerican cities, Monte Albán was a cultural center of the Olmec, Zapotec, and Mixtec people over the course of some 1,500 years. Around the 8th century, the farmland dried up and the rains were so scarce that the city began to suffer the consequences. Before abandoning the city, the people entrusted their dead to the bat god and the ruling priests never returned. Since then, Monte Albán has been considered a sacred, mystic place.

The abandoned city was unearthed between 1931 and 1939 by archaeologists Alfonso Caso, Ignacio Bernal, and Jorge Acosta. The site has been open to the public since then.