American Lake near Aspen
Not far from the popular Cathedral Lake hike in the Maroon Bells-Snowmass Wilderness Area south of Aspen is American Lake. Surrounded by steep cliffs that rise nearly two thousand feet above the lake, this hike is well worth the effort. The trail climbs about 1,700 feet over three and a half miles, and has very good footing most of the way. Once at the lake, it's not difficult to walk its circumference, and something I recommend, since there's nowhere else to go except back down.
The trailhead is a couple of miles shy of the ghost town of Ashcroft, on the south side of the Castle Creek valley.