Exploring a Nike Missile Bunker.

From Underground Ozark's note on the urban exploration of Nike KC-30 missile silo in Pleasant Hill, Missouri:

Without getting specific, we found a non-damaging way to get down into one of the underground chambers ...

After a little while down there, while everyone was milling around doing their own thing, I figured out the elevator, although I didn't immediately know it. I was playing with the controls and noticed that some lights that hadn't been on before were now activated. So, not knowing if it would really work, I hit the button to open the launch bay doors.

The doors came SCREAMING open with a sound somewhat akin to the gates of Hell opening....

Link | Wikipedia's entry on the Nike Missile System