In the 1960s and '70s, a thousand Minutemen II intercontinental ballistic missiles, always at the ready in underground silos spread across the Plains, were just 30 minutes from their targets in the Soviet Union. The missiles have since been retired (though more modern ones still lurk underground across the northern Great Plains). This national historic site preserves one silo and its underground launch facility. The small visitor center is close to the main entrance to the Badlands and uses the same I-90 exit (131).
The visitor center has displays and films that try gamely to cover the entire Cold War. The 30-minute tours cover the nearby underground Launch Control Facility Delta-01, where two people stood ready around the clock to turn keys to launch missiles from this part of South Dakota. The tours require advance reservations and book up weeks in advance in summer (visit www.npsreservations.com/minuteman-missile).
The Delta-09 Missile Silo can be viewed without a tour through a glass cover. It's 15 miles northwest of the visitor center via I-90.