Zhonghua Gate Nanjing

Fourteenth-century Zhonghua Gate has four rows of gates, making it almost impregnable, and could house a garrison of 3000 soldiers in vaults in the front gate building. When walking through the first two gates, observe the vertical indents in the walls. These channels once held vast stone gates that could be lowered into place. Horse ramps lead up the side to the top of the wall, where you can rent a bicycle and ride 2.5km along the wall to Dongshuiguan Park, near Fūzǐ Miào.