This is the oldest library complex found in Sri Lanaka. Pothgul means for a place to store books. This viharaya was build by king Parakamabahu the Great (1153-1185 AD). This was renovated by Queen Chandrawathi. a consort of King Parakarmabahu.
Pothgul Viharaya is a Gedige type structure, build in the middle of the square shape stage. The interesting point in this building is the circular structure in the middle, seems the main library, made out of brick. The circular shape roof even made out of bricks it seems. There are remaining of four small stupas at the four corners of the floor. Out of it there are remaining of the several buildings which were used as awasa ( residential cells where Bikkus live). - Info extracted from SriLankatravelnotes.com