Kahalgaon (formerly known as Colgong during British rule) is a municipality town and one of 3 sub-divisions of Bhagalpur District in the state of Bihar, India.

[3] It is located close to the Vikramashila, that was once a famous centre of Buddhist learning across the world, along with Nalanda, during the Pala dynasty.

The Kahalgaon Super Thermal Power Plant (KhSTPP) is located near the town (3 km).

It is famous for ancient Vikramashila, founded by Dharmapala, a Pala King, in the 8th century, the educational institution served as a learning center of Tantric Buddhism.

The remains excavated from this university made Vikramashila one of the most important historic places near Kahalgaon.

It produced eminent scholars who were often invited by foreign countries to spread Buddhist learning, culture and religion.

Subjects like theology, philosophy, grammar, metaphysics, and logic were taught here but the most important branch of learning was tantrism.

Vikramashila was established by King Dharmapala (rule: 770–810 CE) in response to a supposed decline in the quality of scholarship at Nālandā.

Kahalgaon is connected by a network of national and state highways, along with district and rural roads.

This power plant serves as a beneficiary for West Bengal, Bihar, Jharkhand, Orissa, Sikkim states.

An anonymous tomb on some rocks on the Ganga River nearby is the subject of a painting by J. M. W. Turner (Rocks at Colgong on the Ganges), an engraving of which, together with a poetical illustration by Letitia Elizabeth Landon was published in Fisher's Drawing Room Scrap Book, 1839.

[5] The Kahalgaon Nagar Panchayat has population of 33,700 of which 17,952 are males while 15,748 are females as per report released by Census India 2011.

Kahalgaon Nagar Panchayat has total administration over 6,315 houses to which it supplies basic amenities like water and sewerage.

It is also authorize to build roads within Nagar Panchayat limits and impose taxes on properties coming under its jurisdiction.