One of New York's most beautiful landmarks celebrates its 100th birthday Friday.

Manhattan's Grand Central Terminal, a historic landmark in Midtown, almost didn't see its centennial. The station was spared the wrecking ball in the 1970s, thanks in part to the efforts of Jacqueline Kennedy Onassis.

A temple to transportation, it inspired countless journeys, as the Associated Press recently reported.

The terminal also symbolized "the great era of transportation," said Mickey Jacob, president of the American Institute of Architects. "The grandeur and elegance coming into this space suggested the great adventure beyond."

Since then, it's been restored and updated, and it now serves more than 700,000 people every day.

In early 2012, HuffPost Travel got a behind the scenes tour of the terminal, which revealed some surprising statistics about the now-100-year-old station.

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  • In the middle of the main concourse, the famed opal clock above the information booth is valued at as much as $20 million.

  • Oak leaves and acorns adorn the terminal because they're a symbol of the Vanderbilt family, who financed the construction of the building.

  • The Terminal's main exhibition hall hosts a holiday market and many other temporary events. It books up well in advance but can be rented out -- for $25,000 a day.

  • Every light bulb in the Terminal is bare, in a nod to the Vanderbilt family that wanted to show off the electric power -- and electric railroad -- they'd financed.

  • A "whispering gallery" outside the Oyster Bar relies on brittle Guastavino tile to echo sound from one corner to another, leading many visitors to stick their faces in these corners -- a bizarre sight until you realize they're chatting with a friend across the hall.

  • A fraction of the property held at the railroad's lost and found, which tracks approximately 2,000 items a month.

  • Metro-North's lost and found is among the world's most efficient, with a more than 80 percent success rate in reuniting owners with their property. These are the phones lost as of Jan. 11.

  • The lost and found sees, on average, 300 cell phones a month.

  • The railroad's lost and found is stuffed with umbrellas.

  • Among the oddities at the lost and found include these boots, as well as crutches, bicycles and pieces of framed art.

  • Even more umbrellas at the Metro-North lost and found.

  • A service elevator leads to New York's deepest basement and the converters that power the Metro-North railroad.

  • The "secret" basement known as M42 has three power conversion systems to change AC into DC for Metro-North operations.

  • This clock in the basement -- like all clocks in the Terminal -- is synced to the atomic clocks of the U.S. Naval Observatory.

  • These ticker tapes from 1922 were once used to track train movements. While they and other equipment in the basement, including giant rotary converters, are no longer used, they're still in place as a sort of mini-museum.

  • One of four red off buttons in Grand Central's "secret" basement. Pushing any one of these buttons will shut off all electrical power to Metro-North, including on trains and in the Terminal.

  • Many Metro-North operations happen on the seventh floor of the Terminal, but this elevator panel is one of the only mentions of the otherwise hidden level.

  • Orders for staff hang outside the Terminal's "Situation Room."

  • Inside the Terminal's Situation Room, where MTA officials convene in case of emergency.

  • Inside the Terminal's Situation Room, where MTA officials convene in case of emergency.

  • The Terminal's Situation Room overlooks the Operations Control Center where all trains and tracks are monitored.

  • Inside the Operations Control Center on the sixth floor.

  • One of many information sources inside the Situation Room.

  • Hallways in many of the restricted access areas of Grand Central are narrow and unpolished.

  • The view of the Main Concourse from the eastern window bay.

  • The view of the Main Concourse from the eastern window bay.

  • The view of the Main Concourse from the eastern window bay.

  • The view of the Main Concourse from the eastern window bay.

  • The eastern window bay looks out onto New York's newest Apple Store and Michael Jordan Steakhouse.

  • A divot in the ceiling in the Main Concourse remains from a 1957 display of a Redstone missile that was raised in the hall.

  • An American flag was hung on the south side of the Main Concourse after the 9/11 attacks.

  • A Tiffany glass clock overlooks 42nd Street, which can be seen by opening a window at the bottom of the clock face.

  • Park Avenue from Grand Central's clock.

  • The face of the Tiffany glass clock.

  • The face of the Tiffany glass clock.

  • A view from behind the glass clock.

  • Chalk graffiti in the room that houses the Tiffany glass clock appears to endorse pop singer Ke$ha.