A team of researchers at the National Institute of Anthropology and History (INAH) in Mexico recently announced the discovery of a 2,500-year-old structure that they believe functioned as a solar observatory.

The structure is part of the pre-Hispanic Teteles de Ávila Castillo archaeological site in Sierra Norte de Puebla and has been under excavation by INAH since 2015. Alberto Diez Barroso Repizo, Teteles’s archaeological project director, told the Art Newspaper that Teteles “flourished during the Middle Preclassic period (900BC-600BC) but declined around AD100, possibly because nearby Cantona expanded.” Diez points to the discovery of green obsidian beads as an indication that Teteles, which is along a trade route, was connected to the much larger Mesoamerican city Teotihuacan, since that city controlled a quarry where the obsidian originated.