Hidden Catwalks, Secret Staircases, Tennis Courts: The Unknown World of Grand Central Terminal

New York City’s famed Grand Central Terminal is known for its iconic architecture, but little is known about its collection of hidden features you probably don't know about.

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Consuelo Vanderbilt-Costin, the great, great granddaughter of Grand Central developer William Vanderbilt II, took Inside Edition on a tour of the secrets inside the terminal.

“To think that years ago they had the insight into building something of this magnitude,” she said.

High above the terminal, there are catwalks that employees use to move around without the congestion of the crowds.

"Catwalks are one of the many secrets inside the Grand Central Terminal," she said. 'The employees still use them today to get from one side to the other, but they used to be used for ventilation.”

She also showed off the ultimate people watching experience, a simple window in the catwalk where you can see down into the terminal but it is difficult for anyone to see you from the ground floor.

Above the concourse is a public tennis court. Until 1966, this was the space from where CBS News was broadcast.

Railroad architect Mark Saulnier explained one of Grand Centrals' most amusing secrets — the whispering gallery.

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Standing in one of four corners you can whisper into the wall and be heard clearly by anyone standing in the corner across from you.

There is also a tiny, hidden spiral staircase that leads to private offices right under the iconic clock inside the information booth.

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