September 5 marked the 650th anniversary of the start of construction on Nanjing’s ancient city wall. The first emperor of the Ming dynasty, Zhu Yuanzhang, ordered the city of Jiankang (the former name for Nanjing) to be expanded on Sept. 5, 1366. Construction on the wall lasted over 20 years. Today, the ancient wall has become a symbol of Nanjing. It is also one of China’s largest national treasures. Hundreds gathered at the city wall to celebrate the occasion.