Bagan (formerly Pagan) is an ancient city located in the Mandalay Region of Myanmar. From the 9th to 13th centuries, the city was the capital of the Pagan Kingdom, the first kingdom that unified the regions that would later constitute modern Myanmar (Burma) (Wikipedia).
Architecture of Bagan stands out for not only the sheer number of religious edifices of Myanmar but also the magnificent architecture of the buildings, and their contribution to Burmese temple design. (Wikipedia). A stupa, also called a pagoda, is a massive structure, typically with a relic chamber inside.