We walked around the entire hospital perimeter, trying to find a door that looked like the one we'd peeked out of -one facing the direction we knew the door faced. But no such door existed. So we started looking in the surrounding neighborhood, figuring that the multi-colored tunnel must have left the hospital grounds. Finally, we found it - kittycorner to the hospital was a fenced-in parking lot - and I was sure that the fence surrounding it was the one I'd seen from the doorway. In the lot was this small, white nondescript building - this was where the tunnel emerged from.

With this piece of the puzzle in place, the mysterious tunnel was a lot less so - it had been a pedestrian tunnel for hospital staff, who parked across the streets, but were able to get inside and get to the hospital in the safety and warmth of the tunnel that runs beneath the intersection.

This made a great exit point on future trips - we could emerge from this place, seemingly totally unconnected to the hospital, much more easily than we could sneak out of the hospital nonchalantly.