The most worshiped and the largest is the Tissamaharama Stupa & according to ancient chronicles this stupa has been built by King Kavantissa who ruled Ruhuna in the 1st century BC. But there is also a belief that this stupa was initially built by regional King Mahanaga in the 3rd century BC and King Kavantissa probably enlarged the shrine.
Mahanaga is a brother of King Devanampiyathissa (250-210 BC ). History states that that when Mahanaga was inspecting the construction of Walas Reservoir , the queen of Devanampiyathissa send him a bowl of Mangos with the top most one poisoned. Her intention was to kill Mahanaga to ensure the throne to her son after Devanampiyathissa. At that time the son was with his uncle at the tank and child ate the poisoned mango and died on the spot. Fearing reprisal he took his pregnant wife and escaped to Ruhuna where he built up his own regional kingdom surrounding Magama area.
The more recent restoration work of this stupa had begun in 1858 due to the efforts of Wepathaira Sumana Thera, who rediscovered Thissmaharama Vihara after making a pilgrimage to the area. He built a hut in the visinity of the stupa and started living there to supervise the restoration works by him self. It took 16 years to complete the renovation work of the Garbhaya, semi spherical part of the stupa which is 86 feet in height. But Wepathaira Sumana Thera could not complete the restoration of Thissmaharama stupa in his lifetime and after the death of Wepathaira Sumana Thera in 1873, Walpita Medhankara Thero, a monastic brother of Wepathaira Sumana Thera took over the renovation works. By 1895 Walpita Medhankara Thero managed to complete the restoration of Hatharaskotwa of the stupa and enshrined relics in it. The pinnacle of the stupa was ceremoniously placed in 1900 and work was finally completed in 1915.