I spent the past week hiking around Open Spaces in the Boulder area and this was perhaps the most spectacular one that I did. As other reviewers have noted, one the key things to do is get there early because it is a very popular trail. I also had a few issues finding the Devil's Backbone Open Space because the sign on the road is quite small and my Garmin could not find it at all. The trail itself is an easy walk and you reach reviews of the backbone very quickly. After that point, you can walk several more miles north to the opposite end of the Open Space, but I do not recommend that. Once you are a mile or so past the backbone, the surrounding vegetation and geology is still interesting, but the views are marred by an increasing number of large homes. I just found that depressing. My advice is to walk up to and around the Wild Horse Loop and then back towards the backbone. It's readily walkable at any time of the year.
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