On this day in 1520, faced with an Aztec rebellion against his rule, Spanish conquistador Hernando Cortes fights his way out of Tenochtitlan at heavy cost. Aztec Emperor Montezuma II was killed in the fighting and a vessel carrying Aztec treasure and Spanish soldiers was lost in Lake Texcoco. In 1521, Cortes returned to Tenochtitlan, the seat of the Aztec Empire, and after a three-month siege the city fell. Cuauhtemoc, the new Aztec emperor, was taken prisoner and later executed. His death marked the end of the Aztec Empire. On the ruins of Tenochtitlan, the Mexicans would later build Mexico City.