Secrets of New York City's Grand Central Terminal

Not only is Grand Central Terminal one of the world's most beautiful train stations, it's also one of New York's most fascinating landmarks. Host to more than 250,000 people who pass through it daily, the station is a crossroads for locals, commuters, and tourists from all over the world.

Built in 1913 by Commodore Cornelius Vanderbilt, it was meant to symbolize wealth and power at a time when railroads were making travel easier and more comfortable than ever before. After making a fortune on steamships, Vanderbilt turned his sights to the railroad and had the beautiful, Beaux-Arts station built using sumptuous materials like Tennessee and Botticino marble, brass, opal, and Guastavino tile. Though the famous landmark may seem well-trod by now, these 11 secrets might surprise you.

1. There’s a Bar Hidden Inside

Everyone knows about the Oyster Bar, but did you know there's also a sumptuous lounge inside? Enter the station from Vanderbilt Avenue and make your way to the balcony level. There you'll find a gorgeous bar where waitresses in black dresses, pearls, and red lipstick serve Jazz Age-inspired cocktails and themed concoctions like Prosecco-spiked Grand Central Spritz.

It's called The Campbell. The sophisticated space was originally the office of tycoon John W. Campbell, a friend of Cornelius Vanderbilt. In 2007, it was restored to its former glory, complete with Oriental rugs, porcelain vases, a massive stone fireplace, leaded glass windows, and plush sofas. It's hands-down one of the best hidden bars in New York.

2. There Are Two Valuable Clocks

Outside, on the station's façade, is the world's largest Tiffany clock, weighing in at 1,500 tons and spanning 13 feet in diameter. Made of brass and stained glass, it is surrounded by a statue depicting the Roman gods Mercury, Hermes, and Minerva designed by French artist Jules-Félix Coutain.

Then, inside the main hall, the four-sided ball clock that sits atop the information kiosk is worth an estimated $10 million. Its four faces are made of opal set in brass with a brass acorn on top — the Vanderbilt family's symbol.

3. Oak Tree and Acorn Motifs Are Everywhere

The Vanderbilt family motto: "Great oaks from little acorns grow." Cornelius Vanderbilt wanted everyone to know he was responsible for the magnificent station, so he had French artist Sylvain Saliéres create decorative flourishes of bronze and stone laden with oak leaf and acorn motifs. You can spot them on ornamental carvings in Vanderbilt Hall, on the arches reaching up to the ceiling in the main concourse, and on the giant bronze chandeliers positioned throughout the station.

4. The Whispering Gallery's Origins Are Unknown

In the passageway near the Oyster Bar stands an acoustic marvel known as the Whispering Gallery. Two people standing at opposite corners of the vaulted archway can communicate, their voices reverberating like a game of telephone that no one else can hear. The remarkable vaulted ceiling is made of Guastavino tiled arches, like the Oyster Bar, but no one knows whether this fascinating acoustic effect was intentional.

5. The Constellation Ceiling Is Backwards

In the main concourse, the ceiling was originally meant to be a skylight, but when time and money started to run out, artist Paul Helleu came in to design the fantastical mural instead. A Columbia University astronomer confirmed the artist's design for accuracy, but it turns out the painters put the plans on the floor while they worked, which resulted in the constellations being painted backwards.

6. There Are Tennis Courts Inside the Station

It's a little known fact that the Vanderbilt Tennis Club is on the fourth floor and open to the public. Anyone willing to pay rates of $200 to $300 per hour (depending on the day) can reserve time on the courts and in the fitness center. Racquet rentals are also available.

7. The Windows Have Hidden Walkways

Though this secret is kept tightly under wraps, the giant windows visible from the main concourse have hidden walkways that offer bird's-eye views of the station. They exist so employees who work in the offices above the terminal can navigate it without fighting through the crowds down below. Because public access is highly discouraged, the walkways can be accessed only with a key pass.

8. It Has a Secret Entrance to the Waldorf

A two-story train shed concealed under the station contains 33 miles of tracks — more than twice as long as the island of Manhattan. VIPs who want to avoid the public gaze have used a top-secret track, known as Track 61, to get around. It connects to an elevator that goes directly into the Waldorf Astoria Hotel. One such VIP, President Franklin Delano Roosevelt, is believed to have used it to hide his polio from the public. Track 61 is still kept available for American presidents when they're in town, just in case they need to make an emergency exit from the hotel.

9. There's a Top-Secret Room That Isn't on the Blueprints

It wasn't until the 1980s that officials acknowledged the existence of a top-secret room known as M42, though its exact location remains a well-guarded secret to this day. The 22,000-square-foot chamber 10 stories below the main concourse doesn't appear on any blueprints or maps of the station, and at one time, anyone who attempted to go down there risked being shot by guards. It contains a series or rotary converters once responsible for controlling the electricity that powered the trains connecting the East Coast. If compromised, as the Nazis attempted to do during WWII, the entire railroad system would be crippled.

10. The Station Narrowly Escaped Demolition

By the 1950s, cars and planes became the mode of transportation in vogue. Shortly after, the New York Central wanted to tear the beautiful Beaux Arts station down. Skyscrapers were proposed to take its place, but luckily those plans never came to be. After the original, gorgeous Penn Station was demolished in 1963, preservationists fought to save Grand Central. Most notably, Jackie Onassis and legendary architect Philip Johnson banded together to form the Committee to Save Grand Central Station and succeeded.

11. It Will Become Even Larger

Grand Central may look finished, but the East Side Access Project is set to expand the terminal even further by 2023 at a cost of some $10 billion. A new terminal will allow the Long Island Railroad to stop at Grand Central, making life a lot easier for east side-bound commuters who have to go through Penn Station. A whole new LIRR station will be built underneath Park Avenue, providing connections to the seven subway lines that run through Grand Central. The project includes 40 miles of fresh tracks laid.