Belleville is a city and the county seat of St. Clair County, Illinois. It is also the seat of the Roman Catholic Diocese of Belleville and the National Shrine of Our Lady of the Snows. It is the largest city in the state south of Springfield. Due to its proximity to Scott Air Force Base, the population receives a boost from military and federal civilian personnel, defence contractors, and military retirees.
Belleville has three St. Louis MetroLink stations connecting it to St. Louis and the network via light rail: Memorial Hospital, Belleville, and College.
Illinois State Highways 15, 159, 177, 13 and 161 all pass through Belleville. Belleville is also adjacent to Interstate highways 64 and 255. I-64 is an east–west highway extending from Wentzville, Missouri to Virginia Beach, Virginia and is the major route from Belleville to downtown St. Louis. I-255 is part of a system of expressways that together form a loop around St. Louis.
Belleville has a bicycle trail that runs through the city from Southside Park to South-western Illinois College and Scott Air Force Base; it is mainly used for recreational purposes.
Belleville's area airports are Scott Air Force Base and MidAmerica St. Louis Airport, and the nearest major airport with regularly scheduled commercial passenger service is Lambert St. Louis International Airport.
Belleville has a population of over 44,478 people.
Belleville is a sister city to Paderborn, Germany.