My grandfather worked very closely with a charity group in our city. It had offices in an old building, and back in the day during the Prohibition Era, they built a tunnel going from that building to another building across the street. No one was ever told about it, it was illegal. Then, one day my grandfather and his cohorts discover the tunnel because their neighbor discovered his end and walked right up into their offices. They all decided to block it off.

I wouldn't be surprised to learn that there are similar tunnels in other old cities, such as New York. I wouldn't be surprised to learn that the Cabal knows about these tunnels, and utilizes them.