History & Background
Historical accounts suggest Nilsagar was excavated during the reign of the Pala or early medieval Bengali rulers as a large reservoir, though local tradition also links its name ("Blue Sea") and construction to the Rajbari of the Kaharol zamindars in more recent centuries. Rectangular in shape and fed by natural springs, it was developed by the local government in the late 20th century into a public park with gardens, a small zoo, and boating facilities, becoming one of the most popular recreational spots in the Rangpur region.