This stupa or choten (Tib.: མཆོད་རྟེན་, Wylie: mchod rten) symbolizes the 35-year-old Buddha's attainment of enlightenment under the bodhi tree in Bodh Gaya, where he conquered worldly temptations and attacks manifesting in the form of Mara.
This stupa is not just a souvenir for decoration: it has been also designed for ritual purpose. Each stupa has an openable space that can be filled with proper substances by traditional way.