The Grand Canal(also known as the Beijing-Hangzhou Grand Canal), a UNESCO World Heritage Site, is the longest canal or artificial river in the world and a famous tourist destination. Starting at Beijing, it passes through Tianjin and the provinces of Hebei, Shandong, Jiangsu and Zhejiang to the city of Hangzhou, linking the Yellow River and Yangtze River. The oldest parts of the canal date back to the 5th century BC, although the various sections were finally combined during the Sui dynasty (581–618 AD).
The total length of the Grand Canal is 1,776 km (1,104 mi). Its greatest height is reached in the mountains of Shandong, at a summit of 42 m (138 ft). Ships in Chinese canals did not have trouble reaching higher elevations after the pound lock was invented in the 10th century, during the Song dynasty (960–1279), by the government official and engineer Qiao Weiyo. The canal has been admired by many throughout history including Japanese monk Ennin (794–864), Persian historian Rashid al-Din (1247–1318), Korean official Choe Bu (1454–1504), and Italian missionary Matteo Ricci (1552–1610).
Historically, periodic flooding of the adjacent Yellow River threatened the safety and functioning of the canal. During wartime the high dikes of the Yellow River were sometimes deliberately broken in order to flood advancing enemy troops. This caused disaster and prolonged economic hardships. Despite temporary periods of desolation and disuse, the Grand Canal furthered an indigenous and growing economic market in China's urban centers since the Sui period. It has allowed faster trading and has improved China's economy.
In the late Spring and Autumn period (722–481 BC), King Fuchai of Wu, ruler of the State of Wu (present-day Suzhou), ventured north to conquer the neighboring State of Qi. He ordered a canal be constructed for trading purposes, as well as a means to ship ample supplies north in case his forces should engage the northern states of Song and Lu. This canal became known as the Han Gou (邗沟 "Han-country Conduit"). Work began in 486 BC, from south of Yangzhou to north of Huai'an in Jiangsu, and within three years the Han Gou had connected the Yangtze River to the Huai River by means of existing waterways, lakes, and marshes.