The temple’s name “Budhanilkantha” is the so-called Sleeping Vishnu Temple because Budhanilkantha is alleged to be a deity of Lord Vishnu (also call Narayan or Jalasayana). The deity is shown lying in a sleeping position on the bed of Sesh Naga (serpent) in the cosmic ocean. It is believed that the deity is over 1,000 years old. Budhanilkantha literally means “God of old blue-throat”.

A statue of Lord Vishnu lies with his legs crossed, as if he is floating, in a 13m (43ft) long tank in the temple grounds. In his four hands he holds the four symbols of Vishnu: the chakra (disc), club, conch-shell and lotus flower.

According to ancient history, the idol of Lord Vishnu which was found buried, had been made by the order of the King Vishnugupta of the Licchavi dynasty in the 7th or 8th century. The holy festival in this temple takes place in the months of Baishakh, Jestha and Kartik (April/May/June and Oct/Nov).

A large number of devotees visit this temple to worship Lord Budhanilkantha in Kartik (Oct/Nov) and also in the extra month of the Lunar Calendar that occurs every alternate year. Though it is a Hindu temple, it is equally popular with Buddhists also. A large number of Buddhist devotees come to Naga Panchami, a day devoted to the worship Naga or serpent god.