Xi’an, called Chang’an in ancient times, was an ancient capital and the birthplace of Chinese civilization. It served intermittently as the capital of 13 dynasties over 1,200 years. Xi’an was the first city to open its doors to the world in ancient China.In the Han and Tang Dynasties, it was the center of China’s politics, economy, culture and international exchange.There are a large number of treasured cultural relics and sites in Xi’an. The Terra-cotta Warriors and Horses are honored as"The Eighth Wonder of the World". The Ancient City Wall of Xi’an is the largest, best preserved ruin of ancient city wall in the world. Owing to its brilliant culture, long history, as well as abundant relics and sites, Xi’an enjoys the laudatory title of "Natural History Museum".