Angkor Wat, Cambodia

Angkor Wat, built by King Suryavarman II in the early 12th century, is the world's largest religious monument, covering 400 acres. Its five towers represent the five peaks of Mount Meru, home of the gods, and its galleries contain the longest continuous bas-relief in the world — 800 metres of carved sandstone depicting Hindu mythology. The entire complex is aligned with astronomical precision.