While checking for structural damage inflicted by the 2017 earthquake, archaeologists with Mexico’s National Institute of Anthropology and History (INAH) made a remarkable discovery: a temple located about six feet (two meters) below the top of the Teopanzolco pyramid, a structure the Aztecs dedicated to Tláloc, the Aztec rain god. It was not uncommon for ancient cultures to build upon older structures, but in this case, the archaeologists had no idea a temple was located within.