Underground passageways have been a theme of my dreams since childhood. One source of this dream content (in addition to the contribution of general psychological factors) could be a trip to see the Yankees at Yankee Stadium with my dad when I was a kid. We saw Mickey Mantel, Yogi Berra, Roger Maris and company play. They were ants on the field from the nosebleed seats, but I saw them.  We took the Number 7 to the stadium. To get to the train Dad and I walked up the underground sloping paths, bordered on each side by ancient wire mesh fencing. The path reversed itself in several switchbacks as we went along with the crowd. I remember the mystery and novelty of the walk and the sense, even back then, that we were in an older New York.

Here is a photo that I took in the 1990s, reminiscent that time in 1962.

Underground at Union Square, New York City