Sonepur internationally famous for the large fair held on the occasion of Kartik Purnima, So far as religious aspect of Sonepur Fair is concerned, special significance is owing to the temple of shree Hariharnath and the site of the battle of Gaj-Grah and rescue of the former by Hari During Kartik Purnima Ganga Snan or ceremonial bathing in the Ganga is held by Hindus to be unusually efficacious. On the day of full moon (Kartik Purnima) immense crowd assembles and take bath. The Mela commences on that day and lasts for more than a fortnight. The Shiva temple, Kali temple and other temples and historical religious monuments are situated here and social and economical activities are at the highest peak during the Mela period. People come here to pay their oblation to the lords .It is the largest fair of its kind in the world, for it is a fair specially for the trade of animals. Cattle, horses, camels and elephants can be seen in large numbers. It attracts a huge number of people, not only from all over Bihar, but also from other parts of India and foreign countries.