Plynkes is right. A stupa or chorten is a sort of reliquary/shrine and focus of worship/reverence. In effect it is an almost abstract and highly stylised sculpture of the Buddha seated on a throne. The number of steps/levels are symbolic and highly significant (a fact I found out half way through the build - much to my annoyance!)
As for the building of my models. I made them by constructing a foamcore shell of the main dias and steps and covered it in milliput, then achieved the brick layer effect using a plasticard tool. The dome is foam covered in milliput and the 'spire' is carved balsa with a green stuff finial.
For every period I game I want to have some scenery recognisably idiosyncratic to give the game character.