What historical stories are behind Nanjing's Ming City Wall?

The Ming City Wall, built in 1366, is the world's longest preserved ancient city wall (35 km). It was constructed under Emperor Zhu Yuanzhang to defend against invasions. Key sections include Zhonghua Gate (with 13 gates for defense) and Xuanwu Lake Park (walls integrated with the lake). Visitors can rent bikes to explore ruins and enjoy panoramic views of Nanjing.