The longest canal in the world is the Grand Canal in China. The canal runs approximately 1,200 miles from Hangzhou to Tongzhou, a suburb of Beijing.
Chinese workers began building the canal in 486 B.C. However, the canal did not reach its current length until A.D. 610 when close to 3 million peasant workers finished a section that reached Hangzhou. In 1271, Kublai Khan ordered the canal run directly to the new capital of Beijing, a process that took 10 years and the labor of more than 4 million slaves. The canal was named to UNESCO's World Heritage List in 2014.