The Downsview Lands are comprised of 260 hectares (644 acres). These lands are strategically located in the north central part of the City of Toronto and in the geographic centre of the Greater Toronto Area (GTA). Currently, it is the single largest redevelopment site in the City.
The Downsview Lands are situated on a topographic divide between the Don and Humber Rivers which are two of the larger watersheds within the region. The main headwaters for both are found to the north, concentrated on the flanks of a large terrain feature known as the Oak Ridges Moraine. These watercourses form natural connections between the headwater features on the moraine and their outlets into Lake Ontario. As these valleys come near the Downsview site, minor intermittent tributaries contribute flows, nutrients and energy to these downstream systems. In these middle reaches, the land use is principally urban. Water quality is substantially degraded in both systems. Black Creek, just to the west of the site, is the smallest and most disturbed watercourse in the Humber River watershed.
The site is well served by major arterial roads, some of which are connected directly to the highway system that loops around the City of Toronto. The site is also well served by public transit with a subway station located immediately east of the site at Sheppard Avenue and Allen Road.
The Downsview Lands form a U-shape that is bounded on its exterior perimeter by Keele Street on the west, Sheppard Avenue on the north, and Allen Road on the east. The Bombardier/de Havilland plant and airstrip form the inner boundary of the site. The Canadian National Railway line runs through the site in a north-south alignment and forms part of the boundary with the Bombardier/de Havilland lands. The southwestern boundary of the site is an existing residential area.