The six-mile Durango area loop that starts with 2.5 miles up Animas Mountain is a rocky grind that demands concentration. But the trail around the top of the hill delivers great views of Durango, the Animas River Valley, and the La Plata Mountains.

The trailhead for Argentine Pass (13,207 feet) is at the end of the easy 4x4 Peru Creek Road near Montezuma in Summit County. The pass follows the crest of the Front Range of the Rockies and crosses the Continental Divide. From the top of the pass, strong runners can continue along the ridges to 13,743' Argentine Peak, 13,856' Mount Edwards, or even all the way to 14,278' Grays Peak. The distance to the ridge on the Horseshoe Basin side, accessible only by foot or mountain bike, is 2.6 steep miles; the climb gains 2,000 feet. The trail then continues up Argentine Peak to the Continental Divide. The trail is rocky but in good shape, making it prime terrain for high-altitude adventures. It's also possible to run from the east side of the pass starting at the Waldorf Mine 4x4 road and trailhead.

The Turquoise Lake Nature Trail just outside Leadville is gently rolling but remains challenging due to it’s location 10,000 feet above sea level. With several 14ers as a backdrop, the 12-mile out-and back trail hugs the shoreline of the calm lake. Its epic feel intensifies with the knowledge that the storied Leadville 100 ultramarathon course uses this path twice (at the 10- and 80-mile marks).

A 40-minute drive west of downtown Denver is Mount Falcon Park near Morrison. There are many trails here with fantastic views of the Front Range, Red Rocks Amphitheater, and Denver proper. Some are flat and wide, friendly to mountain bikers and jogging strollers, while others include more strenuous ascents. Runs of three to nearly eight miles can be had by combining trails. The park includes the remains of the home of John Brisben Walker, who developed the Red Rocks Amphitheater. The foundation of the summer home Walker began to build, intended as a retreat for for U.S. presidents, can also be seen. It was this structure that cost Walker his fortune in the 1900s.

Running along the foothills of Boulder, from Chautauqua Park at the north end to Eldorado Canyon Road to the south, the Mesa Trail is a great option. Run it in out and back for a 12-mile outing with 3,250 feet of climbing. You’ll spend most of your time around 5,500 feet, but peak at an elevation of 6,465 feet. Most of the middle miles of the trail cuts through old-growth forest, so it’s shaded. But a mile or two on both ends are exposed, so slather on the sunscreen. From the Chautauqua trailhead, you can add a mile by taking the even more scenic and challenging Bluebell Trail detour. In any case, expect to see rocky outcroppings and the city below this popular trail.