One of the last remaining sections of old-growth forests in Appalachia has incredible 400-year-old yellow poplars that measure as large as 20 feet in circumference, along with huge hemlocks, oaks, and sycamores. Don't expect sequoias, but you're still likely to turn a corner on the trail and gasp with amazement at the scale of these behemoths. If you haven't seen a true virgin forest, you can only imagine what America must have looked like in the early days of settlement. A two-mile trail, moderately strenuous, takes you through wildflower- and moss-carpeted areas. During June, the parking lot is an excellent spot to see the light shows of the synchronous fireflies, which blink off and on in unison.