Denver: Three Sisters
Credit: Kristian Thacker / Getty Images

You won't have trouble finding trails near Denver. At Alderfer/Three Sisters Park, located between the city and the Front Range, rock formations dubbed "The Three Sisters" and "The Brother" poke out of the prairie and offer views of Bear Creek Basin, Mount Evans, and the town of Evergreen. Some 14.9 miles of trails wind through the park, but this spot is far better for bouldering than hiking. Climb to the top and look west toward the more serious summits.