Boulder Creek Path
Boulder Creek Path was named by Runner's World as "the classic city-center run" in its November 2004 issue.
This runner certainly won't argue with that venerable mag. Boulder Creek Path runs 7.5 miles from a spot along Arapahoe Avenue through the center of the city up to a junction with Boulder Canyon Drive (you can run along the road beyond that, but the signs and common sense dictate that the narrow, winding shoulders don't make it a good idea). As a practical matter, you'll probably only want to run west of 55th Street, as the dirt paths worn into the shoulders off the concrete peter out towards 55th (the concrete's still great for biking or strolling, but definitely not running any distance).
West of 55th Street, the path is perfectly level until the western edge of town (Settlers Park), at which point Boulder Creek Path
enters Boulder Canyon and begins a steady climb for the next few miles. The climb is gradual however, the course becomes less crowded,
and the steep walls of the canyon make for some cool shade in the morning or evening on a hot day.