Stupa

Originally, a stupa was a mound-shaped structure which contained relics of the Buddha.

A bell-shaped Buddhist monument, a stupa (Sanskrit for 'heap') is an important form of Buddhist architecture, though it predates Buddhism.  It is generally considered to be a sepulchral monument - a place of burial or a receptacle for religious objects.

At its simplest, a stupa is a dirt burial mound faced with stone.

See also Chedei.