It is believed to be part of a skull rack ... of young male warriors, but also unearthed the crania of women and children, raising questions about human sacrifice in the Aztec Empire.

Said to be the heads of defeated warriors ... Tzompantli, a skull rack some 60 metres (200ft) in diameter which stood on the corner of the chapel of Huitzilopochtli, the Aztec god of the sun ...