The Jetavanaramaya is a stupa, or Buddhist reliquary monument, located in the ruins of Jetavana monastery in the world heritage city of Anuradhapura, Sri Lanka. At 122 metres (400 ft) it was the world's tallest stupa and the third tallest structure in the world[2] when it was built by King Mahasena of Anuradhapura (273–301). He initiated the construction of the stupa following the destruction of the Mahavihara. His son Maghavanna I completed the construction of the stupa. A part of a sash or belt tied by the Buddha is believed to be the relic that is enshrined here.

The structure is significant in the island's history as it represents the tensions within the Theravada and Mahayana sects of Buddhism; it is also significant in recorded history as one of the tallest structures in the ancient world;[4] and the second tallest non-pyramidal buildings after Pharos (lighthouse) of Alexandria; the height of the stupa was 400 feet (122 m), making it the tallest stupa in the ancient world. With the destruction and abandonment of Anuradhapura kingdom in the 11th century, the stupa with others was covered by jungle. King Parakramabahu in 12th century tried to renovate this stupa and it was rebuilt to the current height, a reduction from the original height. Today it stands at 232 feet (71 meters).

The structure is no longer the tallest, but it is still the largest, with a base-area of 233,000 m2 (2,508,000 sq ft).[6] Approximately 93.3 million baked bricks were used in its construction; the engineering ingenuity behind the construction of the structure is a significant development in the history of the island. The sectarian differences between the Buddhist monks also are represented by the stupa as it was built on the premises of the destroyed mahavihara, which led to a rebellion by a minister of King Mahasena.

This stupa belongs to the Sagalika sect. The compound covers approximately 5.6 hectares and is estimated to have housed 10,000 Buddhist monks. One side of the stupa is 576 ft (176 m) long, and the flights of stairs at each of the four sides of it are 28 ft (9 m) wide. The doorpost to the shrine, which is situated in the courtyard, is 27 ft (8 m) high. The stupa has a 8.5 m (28 ft) deep foundation, and sits on bedrock. Stone inscriptions in the courtyard give the names of people who donated to the building effort.