The document discusses Buddhist architecture from the time of Ashoka in the 3rd century BCE to later periods. It notes that Ashoka promoted Buddhism throughout his empire by erecting stone pillars with edicts, as well as commemorating important Buddhist sites. Stupas originated as burial mounds but later came to symbolize various Buddhist concepts. The stupa complex at Sanchi featuring three main stupas, including the Great Stupa, as well as carved gateways and monastic structures, became a major pilgrimage site. Rock-cut cave monasteries also emerged as places for meditation and residence for monks.