Baba Hariharnath is the only temple in North Bihar where Hari and Har are worshiped together. Our Puranas speak a lot about this temple and research is going on to establish its history.
Bihar holds an important place in Indian and Buddhist history. Siddhartha Gautama, Lord Buddha himself, spent most of his life in Bihar and reached enlightenment under a Bodhi tree at Bodhgaya. This is the most important pilgrimage site in the world for Buddhists, and there are many international monasteries in Bodhgaya. It is believed that the temple of Harihar Nath was built by Lord Rama on his way to court of King Janak to win the hand of Mata Sita and later repaired by Raja Man Singh. Finally Raja Ram Narain further modified the temple during the late Mughal period.
These days, Sonepur fair also called Harihar Kshetra Mela is administered by District of Chapra with support from Bihar Govt. and promoted by the Tourism Ministry of Bihar. The administration also arranges health and welfare camps, sanitation, drinking water facilities for the visitors.
The Hariharnath Mandir Nyas Samiti is managing the affairs of day to day life of temple and work on state of art 'yatri-niwas'' is in progress.