Far, far away from the high-speed freeway frontage, midway between Williams and Kingman, 22 miles northwest of Seligman and a dozen miles east of Peach Springs, a large green sign marks the entrance to Grand Canyon Caverns (928/422-3223, daily, $20-100), which has somehow managed to survive despite being bypassed by the I-40 superslab. Once one of the prime tourist draws on the Arizona stretch of Route 66, the Grand Canyon Caverns were discovered and developed in the late 1920s and still have the feel of an old-time roadside attraction. Tours start every half hour at the gift shop, where you hop on the elevator that drops you 200-300 feet to underground chambers, including the 18,000-square-foot Chapel of the Ages. Regular tours last around 45 minutes. Back above ground, there’s also a gas station and a motel. If you want a truly unique experience, ask about staying overnight in the Cavern Suite, a fully furnished two-bed suite dating back to the 1962 Cuban Missile Crisis, when a corner of the caverns was set up as a fallout shelter.