In ancient Chinese city planning, moats and city walls were built as one system—a line of defense that also helped control flooding. Today, following these old waterways allows us to trace the vanished outlines of Beijing's walls and imagine how the city took shape across different dynasties. From the vision of the Yuan capital laid out more than 700 years ago, to the towering watchtowers of the Ming era (1368-1644), the Grand Canal once flowed past these fortifications and carried the city outw