Sinhala translation of Twin Ponds is known as Kuttam Pokuna. It is located in Anuradhapura and an evidence for the best ancient hydrological architecture. The ponds were built during the era of King Aggabodhi for monks. Abhayagiri monastery monks used these twin ponds for bathing purpose and to relax along the steps. Although these ponds named as “Twin ponds” they are not physically identical. The two ponds differ in their lengths such that Southern pond is greater than Northern pond nearly by 41 feet and depth differs nearly by 3 feet. By using the steps or staircase, one can reach the bottom of the ponds. The water supply to the ponds were transferred from three reservoirs or water tanks named Tissawewa Basawakkulama, and Nuwarawewa along pipelines connected under the ground. First, the water filled to a tank which was built above the ground level of twin ponds. Then the smaller pond was filled by water through “makara kata”, mouth of dragon from that tank. Now finally the larger pond filled with water from the smaller pond through a small opening which located below the ground level. This is nearly equal to present underground pipeline system. It is clearly seen that the ancient architect handled a good way to filter the water. The statue which considered as the guardian of water (Statue naga – a snake with 5 heads) located at the entrance of ponds’ staircase. Water was diverted to Malwatu Oya, which stream along the North central part of the country to empty or clean the ponds. Although the architect of this Kuttam Pokuna is untold, the creativity behind him is still surprisable. Without the modern Engineering equipments and technology it is still unbelievable, to those who visit Kuttam Pokuna. Kuttam Pokuna is one of the best archaeological evidence left in Sri-Lanka to prove the talent of our ancestors.