Nanjing City Walls
When the first Ming emperor made Nanjing his capital, he fortified the city with massive walls. Only some parts of the wall remain but what does remain is staggeringly huge and in good condition. It took an army of 200,000 workers some 21 years to move the 7 millino cubic metres of earth to build the walls. The Nanjing City Walls count amongst the largest city walls ever constructed in China.