This 150-some-year-old railroad-turned-automobile tunnel beneath Park Avenue is normally off limits to pedestrians, but the city DOT has decided to open it to foot traffic as part of this year's Summer Streets, "an annual celebration of New York City’s most valuable public space—our streets. On three consecutive Saturdays in the summer, nearly seven miles of NYC’s streets are opened for people to play, walk, bike, and breathe." It's the first time the public has been allowed to walk through the tunnel since the 1930s (or ever, depending on your source).
Day 589
Park Avenue Tunnel
August 10th, 2013
I did not see you, Matt! But I did see the set of stairs near the end of the tunnel, probably leading to an abandoned station from before. http://www.flickr.com/photos/76807015@N03/9657680497/in/set-72157635274573733
Yes, the stairs are remnants of a station at 38th Street. More info here; old photo here.
That is so cool, thanks for the links Matt! Have a great walk today!