From Route 66 to the bright lights of Las Vegas, the USA is overflowing with wish-list experiences. It also, intriguingly, has many places that can’t be experienced at all, such as top-secret military bases, high-security prisons, clandestine islands and undercover clubs. These are the hidden and off-limits spots that most people will never see – and, in some cases, that’s probably for the best.

Read on to discover some of the fascinating places in America that tourists are forbidden to visit...

Ever heard something described as being ‘like Fort Knox’? Well, that's because the actual Fort Knox is one of the most impenetrable places in the world. Spanning almost 110,000 square feet (10,219sqm), the United States Army installation straddles three counties – Meade, Hardin and Bullitt – in northern Kentucky and is home to 147.3 million oz (4.2m kg) of gold bullion. That’s about half of the US Treasury’s stash. For obvious reasons, the site is closed off to the public and highly secure. In fact, it’s like Fort Knox.

North Brother Island has a chequered past, to say the least. The island, on New York's East River in the Bronx, was uninhabited until 1885 when Riverside Hospital (pictured now) was built for people carrying contagious diseases. In 1905, more than 1,000 people died when the General Slocum steamship caught fire near the island. Two years later ‘Typhoid Mary’ Mallon, the first American known to carry typhoid fever, was quarantined and eventually died here in 1938, having contracted pneumonia. The island is now a protected bird sanctuary, closed to the public. Access requests are available but under specific conditions only and are rarely permitted.

Perched atop a basalt stack in the Pacific Ocean, Tillamook Rock Lighthouse is nicknamed ‘Terrible Tilly’ – and for good reason. It was built in 1881 and, before work even began, the master mason surveying the site was tragically swept to sea. A storm during construction meant workers were stranded on the rock for a fortnight without supplies and in January 1881, just before completion, a ship wrecked nearby killing all 16 crew members. Closed for good in 1957, Tilly is considered too dangerous to visit but you can see her from the beach at Tillamook Head.

Hawaii’s so-called ‘Forbidden Island’, Ni’ihau lies around 15 miles (24km) off the coast of Kauaʻi and is home to just 170 people. The invite-only destination has mystified tourists for years. Its extreme exclusivity is down to a promise made by Elizabeth Sinclair when she purchased the island from former Hawaiian king, Kamehameha V, agreeing to protect the land from outsiders. Today it’s owned by her great-grandsons, Keith and Bruce Robinson, and remains closed off to wider society. Surrounded by rich azure waters, Ni'ihau appears to be as spectacular as it is enigmatic.

If you owned a recipe worth billions of dollars, you’d probably do everything in your power to keep it under wraps. That's exactly what The Coca-Cola Company is doing with the legendary secret formula for its most iconic soft drink. The Coca-Cola Vault can be found inside World of Coca-Cola in Atlanta, Georgia and touring the museum’s exhibit is about as close as you can get to the top-secret recipe. Carefully guarded, the recipe lies protected inside a bank-like safe that only a handful of people can access.

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Fans of American political thrillers and crime dramas are likely to have heard of Langley – and know the mystery that shrouds this impenetrable complex. Officially named the George Bush Center for Intelligence, this is the headquarters of the Central Intelligence Agency (CIA). Langley is, of course, closely guarded and entirely off-limits to all but those with the highest levels of security clearance.

Unless you're one of America's wealthiest and/or most powerful men, it's likely you'll never find yourself in Bohemian Grove, California. The restricted 2,700-acre campground hosts a sort of summer camp for the Bohemian Club, a private organisation based in San Francisco that has counted numerous US presidents and celebrities among its members, including Ronald Reagan, George W. Bush and Clint Eastwood. The secret society was founded in 1872 and its male-only members meet in the campground, shown in this aerial shot, annually.

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If you've ever been to the Disneyland Park in Anaheim then you may well have walked through New Orleans Square, a replica of Louisiana’s iconic city. Somewhere here you’ll find Club 33, a members-only destination that's shrouded in mystique. The club was originally created as a place for Walt Disney to entertain important guests but he passed away shortly before it opened. Now the invite-only club has a waitlist and it’s said membership costs include an initiation fee of £26,000 ($33,000), followed by £12,000 ($15,000) a year.

Somewhere in the spectacular natural landscapes of Utah’s Salt Lake County is an ultra-secure vault belonging to The Church of Jesus Christ of Latter-day Saints, or the Mormon Church. The Granite Mountain Records Vault lies 600 feet (183m) inside the rock of Little Cottonwood Canyon and houses the world’s largest collection of genealogical records. For this reason, no public access is allowed and few know exactly where the facility is.

Thanks to movies including The Wolf of Wall Street and The Big Short, many of us have become fascinated by what goes on inside the New York Stock Exchange. This high-profile building has been closed off to visitors since the September 11th attacks and increased security now makes it impossible to get too close. You can, however, soak up its splendour from the outside, see the iconic Charging Bull statue and tour the gold vault inside the Federal Reserve Bank, located a few blocks away.

Despite falling within British Indian Ocean Territory, Diego Garcia – the largest of the Chagos Islands – is an important if controversial part of American security. The US military began creating secure facilities, including an air and naval base, in the 1970s, evoking opposition from states keen to preserve the region’s non-militarised status. Numerous air operations were launched from Diego Garcia during the Persian Gulf War in the early 1990s and it played a critical role at the start of the Iraq War in 2003 too. There's no permanent population on the island and it remains off-limits to anyone other than military personnel.

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Could ADX Florence be America's most secure building? The penitentiary in Colorado’s Fremont County is the country’s only ‘supermax’ facility, referring to its extremely high levels of security. It’s home to prisoners deemed too dangerous for regular incarceration and inmates here are said to be kept in solitary confinement for up to 23 hours a day. In fact, so secure is the facility that very few images of it exist. This 2021 photo shows the exterior and incongruous Rocky Mountains backdrop.

Discover America's eerie abandoned prisons

The legend of Dulce Base has long rumbled on with rumours of cattle mutilation and alien abductions connected to an underground lair within New Mexico’s Archuleta Mesa mountain range (pictured). The site, near the small town of Dulce, is said to be a top-secret military base and over the years locals have reported hearing strange noises and witnessing unexplained lights emitting from the base. Some believe the area is jointly run by aliens and humans.

In 2016, publications around the world began discussing the secret spy hubs believed to be dotted across America. The buildings are apparently operated by the National Security Agency and this one, the near-windowless 33 Thomas Street (formerly the AT&T Long Lines Building) in Manhattan, is said to be just one of eight, with the others in Atlanta, Chicago, Dallas, Los Angeles, San Francisco, Seattle and Washington DC. Few know exactly what goes on inside.

Located in the Hamptons’ Peconic Bay just off Long Island, this private isle is not only extremely valuable – it’s impossible to access. The 435-acre teardrop of land belongs to billionaire businessman Louis Bacon and is thought to be worth around £369 million ($500m). No one quite knows what goes on there – not even the area's police department, according to the New York Post.

This infamous prison island looms in the middle of the East River between Queens and the Bronx. It’s been home to New York City’s main jail complex since 1932 and has gained a reputation for brutality and mistreatment. The likes of David Berkowitz (the serial killer known as Son of Sam) and Sex Pistols’ Sid Vicious were incarcerated on Rikers and today it remains one of America’s most notorious prisons. Perhaps it's a good thing that tourists aren't allowed anywhere near. Plans were afoot to close it in favour of building four smaller borough-based facilities, although that is unlikely to happen before 2027, according to The New York Times. 

Controlled by the Federal Emergency Management Agency, this sprawling facility – used to support emergency management operations – is located on a 434-acre site and run by 240 employees. Mount Weather Emergency Operations Center has important communication links with the White House and reportedly includes an underground bunker with its own hospital, crematorium and emergency power plant. Today, Mount Weather is home to six major disaster operations facilities and remains off-limits to civilians.

Just one look at this creepy farmhouse might be enough to encourage you to stay away, but the abandoned building on the east side of Seneca Lake, the largest of the Finger Lakes, has long fascinated locals. The mysterious property has sat empty for decades, with towering poison ivy vines slowly crumbling it to the ground. Rusting vintage cars, consumed with greenery, only add to the eeriness. It’s still a restricted private property today.

If you ever find yourself in Colorado’s El Paso County, you could be within touching distance of Cheyenne Mountain Air Force Station, which dominates the Cheyenne Mountain Complex. This was used as a control centre for the defence against the Soviets during the Cold War and today it's said to be a training site for the US Air Force. Hidden inside the mountain itself and only accessible to those with the highest levels of security clearance, what goes on inside remains somewhat of a mystery.

This notorious detention facility is actually in Cuba but it’s an important United States military prison, located within the Guantanamo Bay Naval Base. Highly secure, the isolated camp has become synonymous with torture and detention without trial, with some prisoners held there indefinitely. Cloaked in controversy since the first detainees were transferred to the prison camp in January 2002, this is one place you probably wouldn't want to visit, even if you could.

Area 51 has long been a source of fascination – yet the US government only officially recognised its existence in 2003. The top secret US Air Force facility drew attention during its Cold War-era aircraft testing and has been at the centre of several extra-terrestrial conspiracy theories including that the moon landings were staged and that there’s a lab run by aliens. It’s still operational and strictly off-limits, though those curious to know more can visit the nearby Alien Research Center, a metal hangar filled with curios and gifts.

These are America's most mysterious places