The southern gate of Nanjing's city wall; this massive gate is one of the best preserved parts of Nanjing's city wall, and one of the best remaining examples of early Ming defensive architecture extant anywhere. The wooden castle at top was destroyed by fire, but the immense masonry (each complete with the mason's name and home province by order of the emperor) substructure remains. Two courtyards contain an archery range and vegetable gardens. The main gate has three immense depots within where, long emptied of provisions, you can find some scale models and exhibits about the gate. In one depot you can find an air raid siren used during the Japanese attack on the city.