Kallanai Dam Kallanai (also known as the Grand Anicut) is an ancient dam built by Karikala of Chola dynasty in 150 CE. It was built (in running water) across the Kaveri river flowing from Tiruchirapalli District to Thanjavur district, Tamil Nadu, India. The dam is located in Thanjavur district 15 km from Tiruchirapalli and 45 km from Thanjavur. It is the fourth oldest water-diversion or water-regulator structure in the world and the oldest in India that is still in use because of its spectacular architecture, it is one of the prime tourist spots in Tamil Nadu. The dam that was built 2,000 years ago by the king still stands strong where the Cauvery and Kollidam rivers join providing water to the delta districts. Karikal Cholan ruled his Chola kingdom with Uraiyur in Trichy as his capital. The Grand Anicut, an engineering marvel which he built, helps irrigation in the delta region, the rice bowl of Tamil Nadu. It helps divert excess water to the Cauvery, the Vennar and the Kollidam rivers and the Anicut canal, benefiting lakhs of agricultural lands. During the British era, Sir Arthur Cotton added regulators for the Grand Anicut, which withstood the test of time. Photos Temple Ponds Temple Ponds are traditional rain water storage structures built near the temples. In olden times, the water in the ponds was used for drinking purpose. In recent days it is used for Rain water conservation.

It may be noted that all these temples are more than 1800 + years old and some even more than 5000 years Temples when constructed were at that time mega infrastructure projects of the time. These Temples catered to the religious aspect of Humanity along with the promotion of cultural activities, academics , arts and knowledge sharing in science and medicine. Care at that time was also given to cater to the requirements of devotes for generations to come and so along with the Temples,  the ponds were constructed.  Just as Ponds , man-made lakes ageing 1000 + years old were constructed by Tamil Kings one such begin the world’s oldest is also given for reference Lake name : Veeranam Lake (Veeranarayanapuram Lake) Located in Cuddalore district in the state of Tamil Nadu in South India As the length is 14 km this is the longest man-made lake in the world. The credit goes to ancient people who have done this job with ordinary hand-made tools. Veeranam Lake was built in the Tenth Century during the time of Greater Cholas, from 907–955 AD and is an 16-kilometre (9.9 mi) long dam in northern Tamil Nadu.