Located approximately six kilometres south of the provincial capital of Thakhek, close to the road to Savannakhet, That Sikhottabong is one of the most sacred sites in Laos. The site itself is believed to have been the location of the Mon city of Sri Gotapura; the remains of many temples and other buildings dating from the Mon era may still be seen in and around the complex. A stupa was clearly in existence here before the 16th century, when it was renovated twice - firstly in 1539 by King Phothisarath and then again in 1566-1568 by his son Sai Setthathirat I. Since that time it has undergone numerous other restorations, notably in 1806 under King Anou and most recently in 1963. The official opening of the stupa in February 1568 is still celebrated today in the three-day That Sikhottabong Festival, which features a wide range of games, competitions and performances by local artists and arts groups. The 28.89 metre, four-sided stupa stands on a 1.5 metre base. Like Phra That Luang in Vientiane and That Inhang in Savannakhet, the stupa is surrounded by a cloister wall.