The International Commission on Irrigation and Drainage (ICID) has designated three historic water bodies in Tamil Nadu as World Heritage Irrigation Structures for the year 2021: Grand Anicut, Veeranam Lake, and Kalingarayan Anicut.
Karikala Cholan built the Kallanai Dam (Grand Anicut) in the 2nd century AD. The 2,000-year-old dam is India's oldest and the world's fourth oldest. The Cauvery River Dam is 329 meters long, 20 meters broad, and 5.4 meters high. It irrigates 13,20,116 acres in delta districts and was made using unhewn stones and interlocking technology.