For a while, I lived on Court Street in Brooklyn, NY, and sometimes shopped in the Middle Eastern markets on Atlantic Avenue, which crossed Court Street several blocks from my apartment. I loved fig jam, and it was the only place I knew to get it. What I didn’t know was that, not too long before I moved there, a man named Bob Diamond had found the oldest subway tunnel in the world. I probably trod on its entrance, a manhole at the intersection of Court St. and Atlantic Avenue. There’s great stuff down there. The tunnel linked the Long...