The mysterious multi-colored craziness of a tunnel leading from the basement.

This really was odd to discover - we heard it was a tunnel before we saw it was ... it looked like a hallway, but echoed like a tunnel. The walls were bare cement, adorned with black-bordered squares of color. The tunnel went on for awhile, before ending in a stairwell going upward. At the top of the stairs was a door. The door opened up to the outside. But it was really exposed to the surround apartments and well lit - we couldn't quite tell where the heck we were - so made note to walk around the hospital and figure out where this door came out.  More on that later ...