The Dhamek Stupa was built ca. 500 AD to replace an earlier structure commissioned by the great Mauryan king Ashoka in 249 B.C.E., along with several other monuments, to commemorate his pilgrimage there. Stupas originated as circular mounds encircled by large stones. King Ashoka built stupas to enshrine small pieces of calcinated bone and other relics of Buddha and his disciples. An Ashoka pillar with an edict engraved on it stands near the site.
The Dhamek Stupa is said to mark the spot of a deer park (Rishipattana) where the Buddha gave the first sermon to his five disciples after attaining enlightenment, "revealing his Eightfold Path leading to nirvana". The stupa was enlarged on six occasions but the upper part is still unfinished. While visiting Sarnath in 640 AD, Xuanzang recorded that the colony had over 1,500 priests and the main stupa was nearly 300 feet (91 m) high.
In its current shape, the stupa is a solid cylinder of bricks and stone reaching a height of 43.6 meters and having a diameter of 28 meters. It is the most massive structure in Sarnath. The basement seems to have survived from Ashoka's structure: the stone facing is chiseled and displays delicate floral carvings of Gupta origin. The wall is covered with exquisitely carved figures of humans and birds, as well as inscriptions in the Brāhmī script.