Detail of the "Huei Tzompantli", an Aztec skull tower dating from the end of the 15th century, discovered in Mexico City • AFP These are 119 new human skulls, impaled horizontally, which have just been exhumed in the basement of Mexico City, the ancient capital of the Aztecs, Tenochtitlán, which was built from the XIV e century. In total, more than 600 skulls have been unearthed since 2015, the year of the first discoveries by Mexican researchers from the National Institute of Anthropology and History, who are continuing their excavation. The bones form two towers with a diameter of 4.40 m and a height of 1.70 m, solely made up of these skulls. These strange constructions belonged to the great tzompantli , a thirty-meter wall of skulls that would have frightened the Spaniards when they discovered it during their conquest of Mexico and the Aztec capital in 1521. The historical chronicles, and in particular the accounts of the companions of Hernán Cortés, the famous conquistador, evoke this tzompantli which stood within the grounds of the Templo Mayor, the largest ceremonial center of the Aztec people, in the heart of Tenochtitlán:the god of the Sun, one of the main deities of this civilization, was worshiped there. Anthropologists were surprised to find the presence of skulls of children and women. According to them, for the Aztecs, these skulls were seeds that were to ensure the survival of humanity. They would not have been intended to frighten humans, but rather to celebrate life, while serving as offerings to the gods. Slaves, prisoners of war, convicts and even some volunteers who wanted to be deified in this way were the main victims. The conquistadors destroyed the temple, citing this practice of human sacrifice to justify their actions. Aztec religion was a mixture of polytheistic, animistic and shamanic traditions. Its sacred practices remain mysterious.