Thuparama dagoba in Anuradhapura
Thuparama was the first dagoba to be built in Sri Lanka (its name means simply "The Stupa"), though by later Anuradhapuran standard it's a modest affair, standing less than 20m high. It was constructed by Devanampiya Tissa shortly after his conversion to Buddhism at the behest of Mahinda, who suggested that the new Sinhalese faith be provided with a suitable focus of worship. A monk was dispatched to Ashoka, the Buddhist empeor of India, who obliglingly provided Devanampiya Tissa with two of his religion's most sacred relics: the Buddha's right collarbone and alms bowl. The bowl was sent to Mihintale, whilst the bone was enshrined in the Thuparama, which remains a popular pilgrimage site to this day. By the seventh century, the original structure had fakllen into ruins; Aggabodhi II had it restored and converted into a vadatage (circular relic house), a uniquely Sri Lankan form of Buddhist architecture, with the original dagoba being enclosed in a new roof, supported by four concentric circles of pillars of diminishing height. The roof has long since disappeared and the surviving pillars now topple unsteadily in all directions.