The biggest Buddhist stupa in the area of Kathmandu is part of a large temple compound.
The Great Stupa (in Tibetan, Jarung Kashor) at Boudhanath is the largest stupa in Nepal and the greatest center of Tibetan worship outside Tibet. Located five kilometers from Kathmandu, the stupa is noteworthy because of its square base. It is 36 meters high and the base measures 100 meters on each side. It is a United Nations Educational, Scientific, and Cultural Organization (UNESCO) World Heritage Site. In addition it continues to be a popular site of worship. Thousands of people can be seen circumambulating the stupa all day. A treasure text concerning the Great Stupa and the Tibetan sage Padmasambhava was found and rediscovered in the 16th century. The connection between Padmasambhava and the stupa is strong. He prophesied the stupa would deteriorate as a result of the laxity of moral practice and would require a devout hero to rebuild it. The stupa was built in the fifth century C.E. in the reign of Manadeva. Since the 19th century the stupa has been managed jointly by Bazra (Vajra) and Chini (Chinese) lamas. This arrangement probably reflects competition for power between Tibetan monks and local landowners. When Tibetan refugees flooded into Nepal after the Chinese annexation of Tibet in 1959, many settled in the vicinity of Boudhanath. And since the discovery of Nepal as a travel destination on the “hippie trail” of the 1960s, the area has also become a vibrant center for travelers.
Edward Irons, “Encyclopedia of Buddhism”