Tissa Wewa (Anuradhapura)

Tissa Wewa, an artificial reservoir, was built by Devanampiya Tissa (3rd century BC) in order to increase the water supply to his capital city of Anuradhapura. Only Panda Wewa (5th century BC) and Abhaya Wewa (5th-4th century BC) are older.

Source: Wikipedia — Tissa Wewa (Anuradhapura) (CC BY-SA 4.0)