MEXICO CITY, MEXICO—At the foot of the Great Temple at the site of Tlatelolco, archaeologists from Mexico’s National Anthropology and History Institute unearthed a small offering estimated to be 500 years old, after receiving a tip from a custodian who reported “what appeared to be a buried vessel.” A skull, thought to have belonged to a young, male prisoner of war, was found on top of the vessel. Archaeologist Salvador Guilliem, director of the project, thinks the offering may have been placed there as part of the rituals to prepare the land for the construction of the temple. “We’re marking off the area to see if the offering consisted exclusively of the skull and vessel, or whether there are more remains involved,” he said.