Near Tiruchi, India is the Grand Anicut dam. The people are pushing for it to be recognized with a World Heritage status. The dam was built 2,000 years ago and is still standing and functioning today.
The dam is an engineering marvel and was built by Chola King Karikalan during the first century. The dam is one of the oldest water diversions or water regulating structures in the world in use. The dam is massive and built with uneven stones 329 meters long and 20 meters wide on the river Cauvery. Engineers, historians, and tourists alike come to visit the dam, but little is actually known about it's history.
They do know the main reason for the dam being built was to divert water from the river to the lands for irrigating crops by way of canals. When it was built, it irrigated about 69,000 acres of land and today it brings water to over one million acres. Other dams have been built in replication of the Grand Anicut dam since it's creation.