after Hindu burial mounds. They were typically a dome set upon a low platform with a single pillar emerging from the top which had 3 umbrella-like discs covering the pillar. The pillar and it's umbrellas would be surrounded by a small fence; a miniature version of the fence that surrounded the stupa itself. The pillar represented the "world mountain" or axis mundi; the pivot of the universe. The 3 umbrellas came to symbolize the Three Jewels of Buddhism. (Buddha, Dhamma, and Sangha) Inside, the stupas were arranged into geometric, magical designs and generally housed sacred relics. Buddhist worship included circumambulation (moving clockwise) around the stupa and the sacred object contained inside.
With the emergence of Mahayana Buddhism, the practice of circumambulation was not prevalent (with Mahayanist Buddhists) as sacreditems were placed in the worship hall and worshiped from the front only as the back of the hall would be blocked off for secret rituals. Robert E. Fisher notes the following regarding a change in style of stupa at Ajanta, India:

The stupa continued to be the focal point of the worship hall, and was now embellished and extended with carvings and additional motifs in keeping with the increased complexities of Mahayana worship. The body of the stupa, the anda, is moved upwards and the base extended to accommodate a large image of the Buddha. The figure is placed between richly carved pillars and surrounded by subordinate figures and elaborate, decorative motifs, typical of the Gupta taste. The pillar and umbrella at the top also gain in complexity,