Went underground recently to do a story on the first subway tunnel ever constructed. It was built in the 1840s as part of the Long Island Railroad (LIRR) but  made obsolete, de-commissioned, and sealed up within 15 years. Then it was forgotten and actually lost until a Pratt student named Bob did the necessary research and “discovered” it in 1980. Click on the photo and scroll down on the WNYC Culture page for the video. Or click here to go straight to the clip on YouTube.