South of Tucson, Arizona, in the desert between Sahuarita and Green Valley, sits the only Titan II missile complex in America that the public can walk into. The Titan Missile Museum preserves a real Cold War launch facility, complete with an inactive 101-foot training missile still standing upright in its silo. It's been a National Historic Landmark since 1994 and opened as a museum back in 1986.

Some odd details make the place genuinely fascinating. The silo door was deliberately left half-open during the conversion to a museum so spy satellites could confirm the missile inside was inert and no threat to anyone. It also means visitors on the above-ground tour can look down into the launch duct through a window. The missile itself was never fuelled or armed, and its propellant tanks have holes drilled in them, plus non-standard Air Force markings, to signal it's a dummy.

To go underground, you book a 45-minute guided tour online — $19.50 for adults 13 and up, $15 for kids 5 and up at time of writing. You'll descend 55 stairs to the silo's second level and the launch control center, connected by a cableway. Here's the chilling bit a guide will demonstrate: two keys, spaced far enough apart that one person couldn't turn both simultaneously, could launch a strike in 58 seconds. One visitor per tour usually gets invited to help the guide turn them in a simulated launch. The real crews — two officers and two technicians — worked 24-hour shifts, unlocked safes with dual combinations, matched emergency codes from the radio, and launched without ever knowing the pre-set, still-classified targets.

The Titan II stood on alert from 1963 until 1987, when the Air Force moved to the Minuteman III missiles it still uses. Of the more than 50 armed Titan sites that once dotted the country, this is the last one left — and the only one you can visit.

If you can't manage the stairs or didn't reserve ahead, a $7 self-guided topside ticket still gets you a look into the silo.

Military-history fans could easily build a whole Tucson trip around this. Pair the missile museum with the Pima Air & Space Museum, which houses WWII bombers and kamikaze trainers, or the Tucson Military Vehicle Museum with its Gulf War tanks and WWI-era tractors. And with mild winter temperatures, Tucson doubles as a solid base for desert camping.

Who's this for? Anyone drawn to dark tourism, Cold War history, or just unusual underground experiences. It's a strange, sobering half-day trip — rehearsing a nuclear launch in a real control room tends to stick with you.