Wall of Skulls at Templo Mayor

A tzompantli or skull rack is a type of wooden rack or palisade documented in several Mesoamerican civilizations, which was used for the public display of human skulls, typically those of war captives or other sacrificial victims. It is a scaffold-like construction of poles on which heads and skulls were placed after holes had been made in them. Many have been documented throughout Mesoamerica, and range from the Epiclassic (ca. 600–900 CE) through early Post-Classic (ca. 900–1250 CE). In 2017 archeologists announced the discovery of the Huey Tzompantli, with more than 650 skulls, in the archeological zone of the Templo Mayor in Mexico city. Source: https://en.wikipedia.org/wiki/Tzompantli