There are many tunnels in New York City. On Sundays, I often see people lined up outside the Brooklyn Trader Joe's to tour the 19th century railroad tunnel. But last week Gothamist (link above) had a story on tunnels for cows in Manhattan. In the 1870s, cows were brought in from a Hudson River dock at the end of 34th Street, and traveled through block-long tunnels to reach the slaughterhouse. Who knew?