Gopalganj is a town, municipality and headquarters of Gopalganj district in the Indian state of Bihar. Modern District of Gopalganj was established on October 2, 1973..GeographyGopalganj district covers 2033km2 in area and ranks as the 26th largest district in the state of Bihar. The district is mostly plains and fertile land. In the district's western part, the Gandak river flows southwards. It is located at, at an average elevation of 66m.DemographicsIndia census, Gopalganj had a population of 54,418.TemplesThawe Mandir, an ancient temple, is situated in Gopalganj district.