Somewhere around the Circle of Creation, a note can be found. Written in big, colorful letters it advertises as follows:
"FIELD TRIP!
If you want to experience a real Cold War fallout shelter, look for red chalk sign at the corner of 9th and H on ____, 7 PM. Snacks and fascinating historical trivia are on me, all you have to bring is a flashlight and an adventurous spirit!
"Take only photos, leave only footprints" applies.
P.S.: Wear clothes you won't miss, the place is dirty as hell"