Part of the Urban Wilderness, this 100-acre preserve is home to the Devils Racetrack, the region's only double-black-diamond mountain-biking trail. One highlight of this 1000yd plunge? A near-vertical 50ft wall ride. But you don't have to be an expert to pedal the preserve. You'll also find a kids-only beginner area with a pump track, plus trails geared to various skill levels.