4. Guastavino Tunnel to the Lost Biltmore Hotel

Sometimes the most surprising finds are in the most unassuming places, like a parking garage. On a visit to Grand Central Terminal, Untapped New York tour guide Justin Rivers noticed the famed arched herringbone pattern typical of Guastavino tile work. This area once part of The Biltmore Hotel, a grand Whitney Warren and Charles Wetmore-designed structure that was built as part of “Terminal City,” a compound of hotels and other buildings connected to Grand Central Terminal that was proposed in the original plans by Charles A. Reed and Allen H. Stem, along with William Wilgus.

One of the hotel’s best amenities was the ease with which guests could come and go using the hotel’s connection to Grand Central Terminal. Guests of the Biltmore arriving at Grand Central Terminal would have their luggage collected from the train by porters and then they would travel via tunnel to an elevator in the hotel’s basement and be carried up into the hotel without ever having to step outside.

The hotel was stripped down to its steel skeleton in the 1980s and all that is left of the original structure are small remnants like this passageway and its iconic golden clock, which can be found in the lobby of 335 Madison Avenue.