Xi'an's City Wall is one of the oldest and best preserved city walls in China and one of the largest ancient military defensive systems in the world.

Construction of the first city wall of Xi'an began in 194 BC and lasted for four years. The existing wall was started during the Ming Dynasty in 1370 and encircles 14 square kilometer of the city.

The City Wall has 18 gates, which are all open for tourists to ascend the wall. No matter which gate you choose to enter, you can tour the whole circle of the wall. [China.org.cn/Photo by Han Bo]