Series of waterways in northern China that link Hangzhou with Beijing.
Some 1,085 mi (1,747 km) in length, it is the world's longest man-made waterway. It was build to enable successive Chinese regimes to transport surplus grain from the agriculturally rich Yangtze (Chang) and Huai river valleys to feed the capital cities and large standing armies in the north. The oldest portion, in the south, may date from the 4th century BC. Expanded over the centuries, it continues to be used today for shipping and irrigation.