Round a lush bend on the Bear Creek Greenbelt trail and you'll find yourself smack-dab in the middle of a thriving prairie dog town. Little heads pop up and out of burrowed holes that dot the wide, open meadow; elsewhere, the cheeky varmints stand still as statues, hoping not to be noticed. This is one of the delightful surprises that make the 340-acre Greenbelt the best urban nature fix in town. Although the 'belt occasionally dives under a busy surface street, most of its approximately two miles of paved and unpaved trail winds around little ponds and through swaths of grassland; horse trails hug the mossy banks of Bear Creek, which flows beautifully in the spring. Start at the Stone House, wander east, and let yourself pretend that the trail goes on forever.