Hidden gems in the USA you never knew about

The 1,250ft Empire State Building has a not-so-hidden secret: a hidden view from the 103rd floor. The 200ft metal tip of the iconic building, where the 102nd and 103rd floors are located, was originally meant to be a mooring mast for airships. Today, it's a vantage point open to VIPs and celebrities. One floor above the glassed-in Top Deck observatory on the 102nd floor, the Empire State Building's 103rd floor is open-air and features a short ledge and vertigo-inducing views of New York, New Jersey, Connecticut, Delaware, Massachusetts, and Pennsylvania on a clear day.

Above Cinderella’s Royal Table restaurant in Cinderella's Castle in the Magic Kingdom, spy the small stained glass windows on the fourth floor that illuminate a special hotel room. The suite is available only for special guests, via seldomly offered contests, and, back when the 650-square-foot suite debuted in 2006, contest winners of the Year of a Million Dreams promotion. Originally intended as an apartment for Walt Disney and his family when they visited Florida, the Cinderella Castle Suite was first used as a storage space and then as an area for telephone operators before it became an ultra exclusive hotel room. The sumptuously-appointed French chateau-style studio includes a foyer, two queen beds, a fireplace, and bathroom with spa tub and starry sky ceiling.

Perched 500ft above the street and atop City Hall in Philadelphia, the bronze William Penn statue is a sight to behold. Cast by Alexander Milne Calder, the 37ft statue weighs 53,000 pounds. The secret here is a hidden hatch in the top of Billy Penn's hat. It's large enough for workers tasked with cleaning the statue every decade to crawl inside. Workers have scrawled their names inside the statue, the tallest statue atop any building in the world.

Originally designed as a storage room, the fifth floor of The Supreme Court Building boasts a basketball court where Supreme Court justices and their clerks play hoops. The hardwood court with plexiglass backboards is smaller than a regulation basketball court and features a seal of the eagle of the Supreme Court midcourt. Adjacent to the basketball court is a gym and weight room. Games are not permitted when 'the highest court in the land' is in session one floor below because the sound can be heard.

Since it was completed in 1965, the 630ft Gateway Arch, the tallest man-made monument in the US, has held a secret. Built to commemorate Thomas Jefferson and St. Louis' roles in the westward expansion of the US, the catenary curve structure was built with a time capsule. Welded to the top of the 17,246-ton steel arch, the time capsule contains 700,000-plus signatures from locals, including schoolchildren.

It might seem an unlikely place for wine cellars, but vaulted chambers to store wine were intentionally added to the plans for the Brooklyn Bridge. The cellars were added as a way to offset the construction costs of the iconic 6,016ft bridge that connects lower Manhattan and Brooklyn Heights and to accommodate an existing wine company on the Brooklyn side and a liquor store on the Manhattan side. There were two wine cellars, one at each granite entrance on each side of the bridge, which are consistently cool and dark, perfect for storing wine. Today, the cavernous spaces are used by the city for storage.

Completed in 1936, Hoover Dam is the highest concrete arch dam in the US. Located at the Nevada-Arizona border, Hoover Dam impounds Lake Mead, the largest manmade reservoir in the US. While the Hoover Dam is impressive on its own, it's also a popular scuba dive spot thanks to a submerged B-29 bomber that ditched into Lake Mead in 1948. Only a few dozen divers get the chance to scuba dive each year. Dives can be reserved in advance through authorized guided tours from Las Vegas Scuba and Scuba Training & Technology Inc.

Beneath City Market’s Whistler Plaza, an expansive farmers market in downtown Indy, are historic Catacombs. The Catacombs are all that remain of Tomlinson Hall, a public building built in 1886 that burned down in 1958. Its basement is what is now known as the Catacombs. The Roman-style ruins do not contain crypts or bones but rather are a series of beautiful brick arches accessible via 30-minute group walking tours.

A train station seems like an unlikely place for a tennis match, but that's just what tennis players will find on the fourth floor of Grand Central Terminal. Open 6am to 2am daily, Vanderbilt Tennis offers instructional and recreational tennis for all ages on one regulation hardcourt and two automated practice courts. Originally, the space was an art gallery. Then, it was a recording studio for CBS. In 1966, it became a tennis center that changed ownership several times (Donald Trump once owned it as a private tennis club) with the current operation open to the public by reservation only.

Arguably the most exclusive place to visit at Disneyland is the members-only Club 33 where memberships are reported to cost $25,000 or more plus annual fees. Club 33 is located at 33 Royal Street across from La Mascarade d'Orleans in New Orleans Square. Walt Disney came up with the concept to entertain special guests after attending the 1964 World's Fair, but died before the club opened in 1967. Members swipe a key card to enter the secret space. After passing through an atrium called Court of Angels, members and their guests can sip cocktails at Salon Nouveau and enjoy multi-course lunches and dinners at Le Grande Salon. On the way out, they can shop for exclusive Club 33 merchandise. There are additional Club 33 locations at Shanghai Disneyland and Tokyo Disneyland and at all four parks in Orlando, Florida. Each club requires its own membership, which can take years to obtain.

The 60ft faces of presidents George Washington, Thomas Jefferson, Theodore Roosevelt, and Abraham Lincoln in Mount Rushmore is a popular tourist attraction, but behind Lincoln's head is a hidden repository for records. Inside at the entryway, a teakwood box has been placed inside a titanium vault that has been covered by a granite capstone. The repository contains 16 porcelain enamel tablets inscribed with information about Mount Rushmore, including why Mount Rushmore was carved, who carved it, the reasons behind the selection of the four presidents depicted, and a short history of the US.

Several of New York's famous landmarks have hidden apartments, like the New York Public Library, which once had apartments in each of its branches for library custodians who fed the coal furnaces and looked after the libraries. One of the most famous secret apartments in New York is above Radio City Music Hall. The opulent apartment with 20-foot ceilings was gifted by Radio City Music Hall architect Edward Durrell Stone and interior designer Donald Deskey to showman Samuel 'Roxy' Rothafel. Today, fans of The Rockettes can book a VIP Roxy Suite Reception or rent the meticulously maintained space for a private event.

Located on the northern end of Washington Square Park, the Washington Square Arch was first conceived in 1889 to celebrate the centennial of George Washington's inauguration. (The first president was inaugurated in New York in 1789.) Locals liked the temporary wooden structure so much that the permanent marble Washington Arch was built a few years later. The interior of the arch is off limits to the public but access is occasionally granted to journalists. A narrow spiral staircase of Guastavino tile leads to the top of the arch where there is a 17-foot-tall attic lit with three skylights and access to the roof, which affords enviable views of Manhattan.

Behind a door in a garage underneath Boston City Hall is the entrance to an abandoned subway tunnel that once connected two defunct subway stations, Scollay Square and Adams Square. Built in 1898, the tunnel was closed in 1963 to make way for Boston City Hall. Scollay Square is now Government Center T stop and Adams Square was demolished. While few have visited the tunnel today, the city of Boston occasionally offers free tunnel tours.

Formerly known as the John Hancock Center, 875 North Michigan Ave is famous for its 360 Observation Deck on the 94th floor, 1,000ft above Chicago, but it also has some secret spots on the 44th floor. The building, which contains offices, commercial spaces, and private residences, has a specialty grocery store, Potash Market, open only to residents along with amenities like a conference center, fitness center, and X-Lounge game room.

Since 1922, the Lincoln Memorial has been an iconic landmark. The neoclassical memorial features a 19-foot-high statue of Abraham Lincoln created by Daniel Chester French. Underneath the memorial's marble floor is a three-story undercroft punctuated with stalactites, which formed from water dripping through the monument's 87 steps. Since the memorial is located on land reclaimed from the Potomac tidal flats, 122 concrete pillars were built to anchor the memorial to the bedrock. The pillars are scrawled with cartoons drawn by the memorial's builders during their breaks.