At one time thousands of lookout towers stood atop the peaks, hills, and flanks of American mountains, providing an elegantly low-tech way to spot forest fires. Advances in radio technology and aircraft surveillance made all but a few obsolete, so beginning in the 1970s the Forest Service began renting the historic structures to campers.
Stargazing, bird-watching, and extreme solitude are the draws, as well as the element of adventure: Many towers are designed to sway with the wind. You can drive right up to all but one of the towers we list, though accommodations tend toward the spartan; you'll need to bring everything you'd take camping except the tent. Rent through the National Recreation Reservation Service (recreation.gov), and pack binoculars.