Downsview Park consists of 231.5 hectares (572 acres) of land in the northwest portion of the City of Toronto and the geographic centre of the Greater Toronto Area. These lands were originally home to de Havilland Aircraft of Canada (1929–1947) and then as the air force base CFB Downsview from 1947 until April 1, 1996, when the base closed. It was also announced that the lands were to be held in perpetuity and in trust as a "unique urban recreational green space for the enjoyment of future generations." The mandate to create the urban recreational green space was given to Parc Downsview Park Inc. (PDP) in 1996 and the title to 231.5 hectares (572 acres) of the Downsview Lands was transferred to PDP in 2006 in order to facilitate the development of Downsview Park. The Department of National Defence (DND) retained 29 hectares (72 acres) of the land to accommodate ongoing military needs. Approximately 150 hectares (370 acres) of the land adjacent to the Downsview Lands (including Toronto’s oldest operational airport) is under the jurisdiction of Bombardier Aerospace. A rail line that is used mostly by GO Transit trains runs through the centre of the Park.