The Ruwanweli Dagoba, literally the "Gold Dust Dagoba," but also known as Mahathupa or "Great Stupa," was conceived by King Dutugemenu in the 2nd century to house Buddha relics on a spot indicated by the Arahant Mahinda. Buddhist monks from all over India are reported to have come for the enshrinement of these relics in 140BC. The Ruwanweli is popularly regarded as the greatest of Anuradhapura's dagobas. It was supposedly some 135 metres high in its original form - although it is considerably shorter today - and it has a diameter of 80 metres. Indeed, it was the tallest dagoba in the world at the time.

It is noteworthy that the dagoba was built in the classic bubble-shape - a bubble floating on water that is. Legend has it that the architect who won the chance to create the sacred building, when asked for his design, called for a bowl full of water. Placing his hand in the water he scooped some up and let it fall back into the bowl. In doing so it formed the characteristic shape of a perfect bubble-on-water, and the architect, pointing to it, declared that this was his design.

The construction of the dagoba began as always with great ritual and symbolism. Dutugemenu stationed himself at the centre of the designated piece of land and ordered a minister to hold the end of a fine rod of silver that was fitted into a gold pivot. The minister was then told to walk round the land describing a circle that would delineate the base of the dagoba. According to the ancient chronicle the Mahawamsa, Dutugemenu then placed in the centre of the circle "eight golden and eight silver vases, and surrounded them with 1,008 fresh vases and with cloth in quantities of 108 pieces. He then caused eight excellent bricks to be place separately, one in each of the eight quarters."

Wishing to gain merit for the construction of the dagoba, Dutugemenu ordered that the labourers should be adequately recompensed and carefully looked after. The Mahawamsa states: "At every gate he commanded to place sixteen hundred thousand kahapanas (coins), very many garments, different ornaments solid and liquid foods and drink withal, fragrant flowers, sugar and so forth, as well as the five perfumes for the mouth."

Although the Ruwanweli was Dutugemenu's finest work, he never lived to see its completion. With the construction of the spire and the plastering of the dome alone remaining, the king fell terminally ill. As Dutugemenu lay on his death-bed in 144 BC, his brother "caused a case made of white cloths to be sewed by seamsters, and enveloped the dagoba therewith. He also employed painters to paint the panelled basement; and upon it were represented rows of filled vases, and ornaments radiating like five fingers. He employed parasol-frame weavers to form the frame of a temporary spire made of bamboo; and in the same manner . . . he formed a parapet round the pinnacle, representing thereon the sun and moon."

Dutugemenu was taken from his death-bed to see how the dagoba would look when it was eventually finished. Filled with joy at the sight, he bowed down to it in worship. Later he exhorted his brother to complete the work and to make offerings there three times a day. After Dutugemenu died he was "seen reborn and standing in celestial form in the car that had come from the Tusita heaven." In this car he travelled three times round the dagoba before passing into "the Tusita heaven."

Each of several succeeding kings added something to the decoration and constructed other buildings in the vicinity of the great dagoba. It is recorded that on one occasion King Batiya Tissa (19BC-9AD) festooned the dagoba with jasmine flowers from pedestal to pinnacle, and on another he literally buried it in a heap of flowers, which he kept watered by means of sophisticated machinery designed specifically for the purpose.

During the 19th and 20th century was completely restored, but the work failed to regain the unique bubble shape of the original. This was not the first time that such work had been carried out, for King Parakrama Bahu I (1153-1186AD) of Polonnaruwa had previously restored the dagoba in the style of the period. Indeed it was Parakrama Bahu who was responsible for the hundreds of modelled elephants standing shoulder to shoulder around the square platform, with only their heads and forelegs appearing.

However, most are modern replacements, apart from a few beside the western entrance. Originally the elephants were modelled in brick, and coated with the hard and durable white enamel, chunam, made of shell-lime and sea-sand. Each had ivory tusks that were inserted into precise holes in the jaws. There are also traces of ornamental trappings, which were executed in bold relief. They differ considerably on each elephant, suggesting great ingenuity on the part of the modellers.

Today, fully restored, the dagoba is reached through one of four gateways that lead into the sandy precincts. Facing the dagoba is a statue believed to represent Dutugemenu. There are also four 8th-century Buddha images carved from limestone housed in a modern shrine. The dagoba is topped by a 60-centimetre rock crystal from Myanmar that dazzles in the sun. The Anuradhapura dagobas feature unusual architectural appendages, known as wahalkadas. These are ornate projecting shrines and there are four of them around the dome. At the Ruwanweli only the one to the west, covered with fine carvings of animals and human figures representing divinities, is original.