Stupas in Nepal date back to the Licchavi period; a stupa is a mound-like or hemispherical structure containing relics (such as śarīra – typically the remains of Buddhist monks or nuns) that is used as a place of meditation. Swayambhunath is one of the oldest known buildings in the country and was likely built in the 5th century. It was built in Swayambhu, Kathmandu, where the land was declared as sacred to Siddhartha Gautama (Buddha), by the 3rd Emperor of the Maurya Dynasty Ashoka the Great in the 3rd century BCE. According to the legends, the stupa came out of a sacred lotus at the centre of Kathmandu when the city was a lake.