Located in the southern part of town, this is the biggest and best-preserved of the city wall's original 13 gates. Built by the Hongwu emperor between 1366 and 1386, the wall, at 33km (20 miles), was the longest city wall in the world, made of uniform bricks cemented with a mortar of lime, sorghum, and glutinous rice. Zhonghua Gate, first built in 1386, actually consists of four rows of gates, the first one 53m (173 ft.) long. Each gate entrance had a vertically sliding stone door lifted with a mechanical winch. Twenty-seven arched vaults inside the first gate could house up to 3,000 soldiers, who were set to ambush the enemy should the latter be so unfortunate as to be trapped within the gates. Climb to the top for some good views of the city, and to gaze at the kitschy fake guards. Along the way, watch for bricks that still bear the carvings of their maker and supervisor. In front of the walls, locals fly kites bought from vendors for ¥8.