There were 6 Titan I ICBM Missile sites in Colorado. They were installed in the early 1960's by President Kennedy to counter the cold war threat of a 'strike first' assault on the U.S. And it was a good thing that he did it, for if it were not for this capability, the Cuba Missile Crisis would have ended very differently. It's a shame that we needed our own 'strike firs' nuclear offensive, but it was the only thing that made Khrushchev back down.
If you look to the East from this cache, under the legs of the power tower you will see 2 of the 3 missile launch pads. Best hours of visibility are in the mornings. The 19 acre site is still intact minus missiles and generators. It was sealed up after it was decommissioned in 1965. The half-round structure sits about 50 feet from the 16" concrete reinforced service entrance used by the crews. They were under the direction of NORAD Cheyenne Mountain which would have directed them to launch their missiles on a command by the President.
Fortunately these missiles were never need, but their presence and capability deterred the soviets from attempting a nuclear strike in a mistaken belief that they could win a nuclear war with the U.S. These bases were eventually De-comissioned and replaced by a more capable Titan II ICBM system. They have been de-comissioned now as well.