Kallanai (Grand Anaicut)

Kallanai, also called the Grand Anaicut, is an ancient stone dam across the Kaveri a short way downstream of Tiruchirappalli. It is credited to the Chola king Karikalan, who is said to have built it more than 2,000 years ago, and it ranks among the oldest water-control works in the world that are still in service. The Cholas built it to turn river water into irrigation channels, and it remains central to farming in the Kaveri delta, feeding a dense network of canals that waters thousands of acres.

Built entirely of stone, the dam is 329 metres long and 20 metres wide and has weathered floods for centuries. Sluice gates along it still regulate the flow. Visitors can walk along the top to watch the water rush below, with paddy fields spreading out on either side, and the shaded Anaicut Park nearby is a common picnic stop.