Tunnel Mountain Trail is Banff's classic short summit walk, close enough to town to do without turning the day into an expedition. The trail climbs steadily through forest to open viewpoints over the Bow Valley, the Banff townsite, the Fairmont Banff Springs, and the surrounding wall of Rockies.
It is popular for good reason: the effort is real but manageable, the route is easy to follow, and the reward feels bigger than the distance suggests. Go early or late for quieter switchbacks, and check Parks Canada trail conditions in shoulder seasons when ice can make the simple hike less casual.