The stupa is the earliest Buddhist religious monument and was originally only a simple mound made up of mud or clay, or a cairn in barren areas, to cover supposed relics of the Buddha. After the 'passing away' of the Buddha his remains were cremated and the ashes divided and buried under eight stupas with two further stupas encasing the urn and the embers.
They evolved into large hemispherical mounds with features such as the torana (gateway), the vedica (fence-like enclosure evolved from the vedic villages), the harmika (a square platform with railings on top of the stupa), chattrayashti (the parasol or canopy) and a circumambulatory around the stupa. From the first century BCE onwards, stupas were incorporated into the hall of the chaitya-griha.
The oldest known stupa is the Dhamek Stupa at Sanchi, India, while the tallest is the Phra Pathom Chedi in Nakhon Pathom, Thailand, with a height of 127 metres.
The stupa evolved into the pagoda as Buddhism spread to other Asian countries. The pagoda has varied forms that also include bellshaped and pyramidal ones. Today, in the Western context, there is no clear distinction between the stupa and the pagoda. But in general stupa is used for a Buddhist structure of India or south-east Asia, while pagoda refers to a building in east Asia which can be entered and which may be secular in purpose.
Fundamentally, a stupa is essentially made up of the following five constituents:
a). A square base
b). A hemispherical dome
c). A conical spire
d). A crescent moon
e). A circular disc
Each of these components is rich in metaphoric content and is identified with one of the five cosmic elements said to make up the entire manifested existence. These are earth, water, fire, air and space.