Kallanai Dam (Grand Anicut)

Grand Anicut, locally called Kallanai, is one of the oldest functioning water-regulation structures in the world. Built across the Kaveri River by the Chola king Karikala Chola around the 2nd century CE, the dam was designed to divert river water into irrigation canals for farming in the fertile Cauvery delta. Instead of storing water like modern dams, it works as a diversion weir that distributes water across different channels.

The structure is about 329 meters long and 20 meters wide, built mainly with unhewn stones placed across the river. Despite its age, the dam still plays a crucial role in irrigation for large parts of Tamil Nadu’s Cauvery delta region. Today the area around Kallanai has been developed with walkways, viewpoints, and small parks, making it a pleasant stop for travelers visiting Tiruchirappalli.