World's first dam was constructed in India. This dam was constructed during 1st century A.D. across the river Cauvery in Tamilnadu by Karikala Cholan. This dam was named as "Kallanai Dam" by Karikala Cholan. Kallanai dam is located 48kms away from the temple town Tanjavur. The height of this dam is 320 meters and width is 60 meters. The most important feature of this dam is that no binding material like limestone or cement were used. It was constructed by the method of interlocking the granite stones. Even today, this dam is capable of storing and regulating water. This dam remains today as a testimony for our ancient engineering expertise. We have to remember one more thing that the world's oldest man-made reservoir Sudarshan Jalasayam was built during 4th century B.C. in the region of today's Gujarat showing another piece of ancient Indian expertise in civil works.