Colorado's Eldorado Canyon State Park packs world-class climbing, hiking, and trail running into a relatively small area. Bands of sheer sandstone tower over a bubbling creek where you can dip your feet on hot days. The park also serves as a gateway to a more expansive trail network that extends all the way to Boulder, Colorado, and beyond.
Start from the parking area just beyond the entrance kiosk. Cross the bridge to wander the base of the cliffs, or hike the dirt road up the canyon for incredible views of orange sandstone speckled with fluorescent green lichen. For a longer hike, connect the Fowler and Rattlesnake Gulch Trails for views stretching across the plains to the East and the snow-capped Continental Divide to the West.
The park is open year-round. It's beautiful in the snow, and the steep canyon walls and wooded trails can provide nice shade on hot summer days. However, spring and fall tend to be the most popular times to visit, as Colorado temperatures tend to be moderate.
You can park outside nearby Eldorado Springs (respect the residents by obeying posted signs) and walk in for a cheaper pass, or shell out for a still fairly inexpensive day-long parking pass. Annual passes are also available. These are by far the best deal if you live nearby and plan on visiting a couple times per year.
The park is dog friendly, though dogs should remain on a leash.