NEW YORK, NY (CNN) -- Today, New York's Grand Central Station celebrates its centennial. The icon remains one of the busiest train stations in the world but nothing turns a century old without its share of secrets.
In "North by Northwest", Cary Grant asked the question millions of passengers have posed since the majestic Grand Central Terminal opened 100 years ago, "What time is the next train?"
Each say, 750,000 people pour through Grand Central. The construction of Grand Central paved the way for multi-levels of track service. And soon the era of luxury train travel arrived.
But as plane travel soared and the railways ran into bankruptcy, Grand Central was nearly demolished. A civic fight led by a former U.S. first lady helped save Grand Central. Jacqueline Onassis said, "If you destroy your past something in people dies."
Now in a New York minute, you can spot a wedding, a modeling shoot, and a squash tournament.
Tour guide Dan Brucker revealed the secrets of Grand Central. Look up! People don't even notice a ceiling to mirror the constellation. Another secret is "The Whispering Gallery" on a lower level. Brucker says, "Even though I am standing 30 feet away from you speaking in a low voice. You can probably hear every word I am saying"
The sub-basement is not even on Grand Central maps and it hums with history. Brucker says, "This is the most top secret location inside Grand Central Terminal. The M42."
More than decades ago, troops stood guard to prevent attacks on the power system. Brucker says, "During the second World War there was a great fear, well founded! That saboteurs, that Nazi spies, Nazi agents would make their way down here."
Out front, the clock face has the world's largest example of Tiffany glass. Though people throughout history have told loved ones 'meet at the clock' indoors above the information booth. Brucker says, During the last 100 years what's the most frequently asked question? Brucker says, "Oh my God...where's the Apple store?"