The Nanjing City Wall, a majestic historical structure in Jiangsu, China, stands as a testament to the city's rich past. Constructed during the Ming Dynasty under the order of the Hongwu Emperor, it took 21 years and the labor of over 200,000 workers to complete. This wall, which once enclosed an area of about 55 square kilometers, was part of a grand defensive strategy against potential invaders and pirates. Today, it is recognized as one of the largest city walls ever built in China, and its remnants continue to attract visitors from around the world, eager to witness the grandeur of ancient Chinese architecture and engineering.