Though in Scott County VA adjacent to Washington County VA, Natural Tunnel State Park is within easy day-trip range of the Tri-Cities and features a cathedral-scale tunnel naturally carved through a limestone ridge — 850 feet long and 100 feet wide — that carried railroad traffic for over a century and inspired William Jennings Bryan to call it the Eighth Wonder of the World. A chairlift descends to the tunnel floor, and a visitor center and camping facilities round out this extraordinary geological park.