It was a long and scary Cold War, with trillions of dollars spent on a game of technological leapfrog. But now that there's a McDonald's in Moscow and children no longer grow up under the threat of nuclear annihilation, what are we left with?

Lots of cool, obsolete stuff, actually. The Southwest is particularly rich in relics: its vast deserts were far from Russian spies and noisy liberals. Many of these places are visitor-friendly, and admission is often free. (Rightly so. We taxpayers already paid for it once.)

I start in Tucson, home to Davis-Monthan Air Force Base, the nation's biggest repository of military detritus. On a blue school bus, I tour the Aerospace Maintenance and Regeneration Center, a 2,600-acre warplane graveyard. Partially covered with a white, spray-on plastic to keep out dust and moisture, some 5,000 aircraft bake wing-to-wing under the sun.

But planes are for wusses: nothing provides that creepy frisson of nuclear brinkmanship better than stepping into a missile silo. To do that, I head south on I-19 to Green Valley, where, from 1963 to 1982, the United States kept one of its 54 Titan II missiles in a constant state of readiness. When they became obsolete, all the Titan silos were destroyed-except one; it became the Titan Missile Museum. At the door everyone in my group is issued a hard hat-blue for boys, pink for girls-and an enthusiastic volunteer leads us inside the fence. We pass refueling tanks and displays of reentry vehicles and rocket engines before peering down the lip of the 146-foot silo at the 330,000-pound messenger of destruction-or is that deterrence?

Finally, we descend 55 steps into the belly of the beast; it's an environment of harsh fluorescent lighting and sickly green paint, once sealed off from the outside world by a series of massive steel doors and labyrinthine security procedures. In the control room, our guide takes us through the launch countdown. We pick up (empty) red folders labeled TOP SECRET, and thrill ourselves silly turning a pair of keys (placed far enough apart so as to require two people) and watching the board light up. Not long ago, this would have spelled the end for a mysterious place still known as Target No. 2.

Emerging topside to find the planet unharmed, I head east, and spend the night at a motel in Las Cruces, in the southwestern corner of New Mexico. In keeping with the trip's theme, I zone in on motels that time has passed by, just outside the city centers. Cheap and clean, they nonetheless betray a few down-at-the-heels touches: hairline crack in the sink, burn marks on the TV.

Come daybreak, I venture north on I-25, a straight-line highway running along the aptly named White Sands Missile Range, where the first atomic explosion occurred, in 1945. Tours are given only once a year, and today is not the day, but I do stop for a chili cheeseburger at the Owl Café in San Antonio (Manhattan Project physicist J. Robert Oppenheimer loved them).

Continuing north, I leave the scrubby desert plain for the Sandia Mountains. Destination: Albuquerque. Outside the National Atomic Museum, on Kirtland Air Force Base, I am dwarfed by a B-52, some Polaris and Minuteman missiles, and an F-105 fighter. Inside, I pose next to replicas of Fat Man and Little Boy, bombs that achieved fame (or infamy, depending on how you look at it) over Hiroshima and Nagasaki, respectively. From there, the exhibits follow the evolution of nuclear terror-A-bombs to H-bombs to submarine-launched thermo- nuclear warheads-accompanied by newspaper articles and cheery Life magazine clippings. In 1966, a B-52 carrying four nukes crashed during midair refueling over Palomares, Spain. Oops!

Making my way north over the Sandia Crest along the scenic 52-mile Turquoise Trail (Highway 14), I wind through old ghost towns and juniper-covered peaks to arrive in Santa Fe. A brass plaque in back of the courtyard at 109 East Palace Avenue marks the site of the original Manhattan Project office.

Few realize Santa Fe played host to a murky spy drama that ignited the arms race. In 1945, at the bridge near East Alameda and Paseo de Peralta, Manhattan Project physicist Klaus Fuchs handed over atomic secrets to Soviet spy Harry Gold. The result was the explosion of Joe 1 in Siberia in 1949 and the end of the U.S. nuclear monopoly.

Nuclear technology and natural beauty mix seamlessly at Los Alamos, another onetime home of the Manhattan Project and still the site of the Los Alamos National Laboratory. Atop the Pajarito Plateau, the Department of Energy grounds are ringed by Bandelier National Monument (with ancient Indian ruins), the Pajarito Mountain ski area, and a plethora of scenic vistas. It's easy to see how, after a hard day designing weapons of mass destruction, a nuclear engineer might find peace in the windswept beauty of the Rio Grande valley.

Because top-secret work still goes on at the lab, most of it is off-limits. But Los Alamos itself has been open to the public since 1954, and I marvel at its Eisenhower-era normality before taking in the Bradbury Science Museum. "The rack"--a model of one of the tall square towers that lowered nuclear bombs into their underground testing shafts--sits next to an interactive video display illustrating what actually happens deep in the earth when a 50-or-so-kiloton baby is detonated.

I complete the loop around the Jemez Mountains back toward Albuquerque, then shoot west on I-40 and north on 93. Finally, I arrive at that bastion of free-market fun, Las Vegas. From here, once a month, the government offers bus tours of Mercury, Nevada, and the Nevada Test Site, 65 miles away. Beginning in 1951, dozens of atomic and nuclear bombs were dropped from planes, lobbed from artillery pieces, and exploded underground in 2,000-foot shafts. In 1992, the United States declared a Nuclear Test Ban, and the fast-and-loose days of the NTS were over. As the bus approaches Mercury-now a semi­ghost town-the guide tells us that, sadly, hard times have forced the bowling alley to shut down.

Then it's off to the dry lake beds where much of the testing took place. We pass close to the remains of bridges, bunkers, and an entire town, dubbed Doomstown, which was built from scratch to see how it would survive an atomic attack. Oddly, what was once America's nuclear playground teems with birds, rabbits, and foxes. As a matter of fact, they're now calling it an Environmental Research Park, and a large sign warns: IT IS UNLAWFUL TO POSSESS, HARASS, TRANSPORT, INJURE, KILL, RECEIVE OR REMOVE A THREATENED OR ENDANGERED SPECIES. (It's not a good idea to pick up any rocks, either.)

Though there are a few roped-off areas with signs saying DANGER: RADIOACTIVE HAZARD, I find it hard to connect to plutonium's threat when bombs are referred to as "devices" and detonations as "events," and the answer to the question "How much radioactivity are we getting from that?" is always, "Within federal limits."

Before we leave, the guide points out a few racks and cranes still in place from tests halted by the ban. Too expensive to recalibrate, they stand frozen, awaiting the day a new Evil Empire will rise and the sounds of bombs--and bowling balls--will once again ring through Mercury.

Davis-Monthan Air Force Base Tucson, Ariz. Bus tours (run by Pima Air & Space Museum; 520/574-0462) 9 a.m. (by reservation only) and 10:30 a.m. Monday and Wednesday; also on Friday from October through April.
Titan Missile Museum 1580 West Duval Mine Rd., Green Valley; 520/625-7736. Open daily from November through April; Wednesday-Sunday from May through October. First tour 9 a.m., last 4 p.m. Reservations recommended.
White Sands Missile Range Off Hwy. 380 near San Antonio, N.M.; 505/678-1134. Tours are given only the first Saturday of April and of October.
Owl Café Hwy. 380, San Antonio, N.M.; 505/835-9946; lunch for two $11.
National Atomic Museum Kirtland Air Force Base, Albuquerque, N.M.; 505/284-3243. Open 9-5 daily. License, registration, and proof of insurance are required for all vehicles entering the base.
Bradbury Science Museum Central Ave. and 15th St., Los Alamos, N.M.; 505/667-4444.
Nevada Test Site 702/295-0944. Tours operate monthly (dates vary) and depart Las Vegas at 7:30 a.m. and return around 4 p.m. Reservations must be made three weeks in advance for U.S. citizens, six weeks for foreigners. Firearms, cameras, binoculars, and recording equipment are prohibited, and you must bring photo ID (with social security number on it).