Somawathiya Chaitya is a Buddhist Stupa situated approximately 45 minutes away from the ancient city of Polonnaruwa. Chaitya premises is called the Somawathiya Rajamaha Viharaya. Surrounded by Somawathiya forest reserve, the stupa is located on the left bank of the Mahaweli River. This wonderful stupa is believed to have been built in the reign of King Kavantissa - Dutugemunu’s father - who ruled Magama. It’s said to enshrine the right canine tooth relic of the Buddha, one of the four tooth relics - which are considered the most sacred relics by Buddhists. Somawathiya is therefore much older than Ruwanveli seya, Mirisaveti Vihara or Jetawanaramaya.

The stupa is named after Princess Somawathi, the sister of King Kavantissa, and the wife of regional ruler Prince Abhaya. The prince built the stupa to enshrine the right tooth relic of the Buddha, obtained from Arahath Mahinda, and named the stupa after the princess. Upon completion of the stupa and other constructions, the prince and princess handed over the temple to Arahath Mahinda and other monks.

Chethiya was reconstructed and finally topped with a “chuda manikya” (gemstone at the top of the stupa) in the 80s, only to be re-abandoned during the Sri Lankan civil war. Villages surrounding the stupa such as Sungavila were attacked by the LTTE and attempts were made to seize the chuda manikya, which failed due infighting and an Elephant attack - an episode that the monks residing there attribute to a miracle. The gemstone was retrieved and was kept safe at the Colombo National Museum until 2002, when it was returned and re-installed at the stupa. An interesting feature of the stupa is the cut-away left by the Department of Archaeology at the side of the stupa, which shows the three different historical stages of renovation.