Denver has a modest trail system in the city that includes nice runs in Washington and City Parks. Nearby Golden on the border of west Denver has many of classic trail runs that locals enjoy, including White Ranch, Apex, Matthew Winters Trail, Mount Falcon and Table Mountain. Many Denverites also enjoy the Open Space areas just down the road in Boulder, such as Davidson Mesa, Marshall Mesa and the Mesa Trail at the foot of the flatirons. Centennial Cone is a challenging loop that is about 30 minutes from Denver up Clear Creek Canyon and is good for a longer run with some serious climbing along the way. Don't be surprised if you see Denver's locals running year round, they love hitting the trails when there's snow on the ground as much as on a warm summer's day!