The Angkor Wat temple complex in Cambodia might be the most astonishing ancient site on earth. Covering an area of more than 400 acres, it is made up of something like 10 million stone blocks intricately carved and stacked into temples, terraces, and galleries. For comparison, Angkor Wat covers three times the area of Vatican City, and is made up of more than four times as many blocks as the Great Pyramid of Giza.