If you hike or bike north on "The Old Putnam Trail" in Van Cortlandt Park in the Bronx, New York City, you will come upon these 13 stone pillars. Surrounded by trees and growth, they are like an American Stonehenge for they have no obvious purpose.
While I was there, two boys on bikes came barreling through and came up short. They were yelling, "Hey, what are these for?" I explained and probably dashed their imaginations forever by my answer. "Do you know Grand Central Terminal in Manhattan?." Yes, they nodded. "That was built by in the 1910's by a huge business of the time, the New York Central Railroad. The trail you were on was the roadbed of one their lines of track. A big consideration for building GCT was what kind of stone they were going to use on the outside of the building. In order to choose which stone they decided to test 13 different types and see how they withstood New York City's climate. That is why they set these pillars by their track here in the Bronx. After a period of time, the railroad decided on the two northern pillars which were made of Indiana limestone. Since the stone came from a quarry that was served by the railroad, it was selected not only because it was durable, it would be the cheapest to transport."
Shaking their heads, I knew I disappointed them with this prosaic explanation. Perhaps I should have told them it was the entrance to Batman's Cave. One of the boys told me to be careful, twice. I don't know if it's because of my white beard or that was I alone, in a park, with a fancy camera. Hmmm.
In any event, if you are a fan of GCT, make like Indiana Jones and pilgrimage to this railroad archeologist artifact.