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 (more modern ones still lurk underground across the northern Great Plains). The first national park dedicated to the Cold War preserves one silo and its underground launch facility.
An impressive visitor center has displays and films about the missiles and the Cold War. Here you get tickets for the tours of 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 30-minute tours require advance reservations (866-601-5129).
The Delta-09 Missile Silo can be viewed without a tour through a glass cover.