Across the Ottawa River, which forms the border between Ontario and Quebec, lies the city of Gatineau, itself the result of amalgamation of the former Quebec cities of Hull and Aylmer together with Gatineau. Although formally and administratively separate cities in two separate provinces, Ottawa and Gatineau (along with a number of nearby municipalities) collectively constitute the National Capital Region, which is considered a single metropolitan area. One federal crown corporation, the National Capital Commission, or NCC, has significant land holdings in both cities, including sites of historical and touristic importance. The NCC, through its responsibility for planning and development of these lands, is a contributor to both cities. Around the main urban area is an extensive greenbelt, administered by the NCC for conservation and leisure, and comprising mostly forest, farmland and marshland.