Your lungs will feel like an inferno and your calves will beg you to quit, but being surrounded by panoramic views of Pikes Peak will make you push just a bit farther. This 10K road race begins on Pikes Peak Highway and ascends at an average grade of five to eight percent just past Crystal Reservoir. Test your mettle—and lung capacity—on one of America's most infamous mountains. Sun 7 a.m.

www.pikespeakmarathon.org.