Towers of ancient city walls in Xi'an, China

• photographed on June 18, 2016. Xi'an 
• (formerly known as Chang’an, and once an imperial capital city) was the eastern departure 
• point for the Silk Road—a hub for traders in China's central Shaanxi Province. These city 
• walls were largely built after the Silk Road had fallen into disuse, after 1500 A.D