The Grand Anicut, also known as the Kallanai is an ancient dam built on the Kaveri River in the state of Tamil Nadu. It is located about 20 km from Tiruchirapalli, it stands as an awesome example of Tamilian Engineering. It was built by the Chola king Karikalan around the 2nd Century AD and is considered one of the oldest water-diversion structures in the world which is still in use. The purpose of the Kallanai was to divert the waters of the Kaveri across the fertile delta region for irrigation via canals. The dam splits the river Kaveri into 4 streams known as KollidamAru, Kaviri, Vennaru and PuthuAru.