Run Denver’s springtime marathon and experience the ultimate urban tour of the Mile High City! 26.2 mile Marathon through the stadium, downtown and along 7 miles of water - 13. 1 mile Half Marathon through Denver Zoo - the fast Urban 10 Miler - 5-person Marathon Relay - or the Colfax 5K in City Park. Run for more than 100 charities! May 17-18, 2014. Choose your event at runcolfax.org.