Many of the ziggurats have been destroyed over the past several thousands of years. The famous huge ziggurat of Babylon was said to have been in ruins by the time Alexander the Great conquered the city in 330 BC. The ziggurat at Chogha Zanbil is one of the last surviving ziggurats. Some ziggurats have been reconstructed or rebuilt. The ziggurat at the city Ur is one that has been somewhat rebuilt.