Cobourg is the largest town in and seat of Northumberland County. Cobourg retains its small-town atmosphere, in part due to the downtown and surrounding residential area's status as a Heritage Conservation District. The downtown is a well-preserved example of a traditional small-town main street. Victoria Hall, the town hall completed in 1860, is a National Historic Site of Canada. The oldest building in the town is now open as the Sifton Cook Heritage Centre and operated by the Cobourg Museum Foundation.