The Trans-Canada Highway provides access to Banff Townsite from the north before it turns south toward Canmore. Two exits serve Banff. On the west is the Mt. Norquay road off ramp, and on the east is the Minnewanka Loop Road and Banff Avenue exit.
The Mt. Norquay exit is the best way to slip into the back side of downtown Banff. Near the exit is the Fenland Trail and the side road to Vermilion Lakes. If you are just arriving in town and are looking for a campsite, take the Minnewanka exit and go south a few hundred meters to Tunnel Mountain Road.
There is also a topographic map on this website of a slightly wider area that shows detail accurately represented for scale.
