This pyramid-shaped, seven storied building called Sathmahal Prasadaya is thought to be an unusually shaped stupa built during the Polonnaruwa Period (11th -13th century).
There are 4 known square shaped stupa’s in Sri Lanka. The most popular is the Sathmahal Prasadaya. The rest of the 3 stupas can be found in the ancient Anuradhapura kingdom which are rarely visited by the pilgrims. One of these stupa’s is Nakha Vehera. The other 2 belongs to the Abhayagiriya Monastic Complex. One of them is known as Indikatu Seya (aka Prasada Stupa). The other lies west of Eth Pokuna on the western border of the Abhayagiri Monastery.
It is said that similar Stupa’s to Sathmahal Prasadaya can be seen in Cambodia and in Siam. It is thought this has been built for the Cambodian soldiers who were working under the king as place of worship. The building has four entrances from four sides. Also there is stair case to reach the upper levels. The person who built it, the original name of it or the purpose is still a mystery.