From national parks to moving monuments, there are plenty of famous and unique places to visit in the United States. However, there are some attractions that are so bizarre, it's hard to believe they actually exist. Whether you have an appreciation for the artsy, want to explore the darker side of human nature, or just want to see what the brain of a genius looks like, here are five unusual destinations you'll want to visit.

The Mütter Museum

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Looking for something a little different from your typical science museum? The Mütter Museum in Philadelphia delivers. According to the museum's website, it welcomes more than 130,000 visitors annually.

The museum also promises to make its visitors "disturbingly informed," so this isn't a museum for the faint of heart. The medical museum houses an extensive collection of doctor's instruments throughout history as well as a collection of anatomical specimens.

Visit the museum to gaze upon sections of Einstein's brain or check out a plaster cast of the liver from famous conjoined twins Chang and Eng. Don't forget to take in the collection of 139 human skulls, gathered in the late 19th century in an attempt to discredit phrenology. The latter is the theory that you can determine a person's character based on bumps on the skull.

All in all, the museum is the perfect place for science lovers and those intrigued by the macabre. If you're easily disturbed, however, be sure to skip the Soap Lady exhibit.

Salvation Mountain

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Located in Niland, California, Salvation Mountain is one man's three-decades old art project. It's basically a man-made mountain, with over 100,000 gallons of paint used in its creation. Leonard Knight, who died in 2014 at the age of 82, started building Salvation Mountain in the California desert in 1984.

Today, Salvation Mountain is a massive structure built from clay, straw, and lots of paint. The mountain stands 50 feet high and is completely covered in Knight's artwork. Knight wanted the art on the mountain to convey that "God is Love," with biblical passages and hearts prominently featured in the artwork. The mountain is still a sight to see, even if you don't hold the same religious views as Leonard did.

Knight lived in his truck on the site when he worked on the mountain and was often available as a guide for visitors. Musical artists such as Coldplay and Third Day have featured the mountain on their albums and in their music videos. The site was even the inspiration for a location in the Grand Theft Auto video games. A must-see for those looking for artistic inspiration or anyone who enjoys being a maverick!

Neon Boneyard

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Where do old neon signs go to die? A lot of them end up in the Neon Boneyard at the Neon Museum in Las Vegas, Nevada. The museum houses a collection of over 200 neon signs dating from the 1930s onward. Many are fully restored and highlighted with ground lighting 24 hours a day.

The museum is best visited at sunset when the working signs shine brightest against the Nevada desert backdrop. It's a photographer's paradise, with plenty of interesting scenes just begging to be photographed.

Tour the area on your own or with a guide. During your visit, you'll see the famous Stardust and Sahara casino signs in all their 1950s glory as well as the Lady Luck sign from National Lampoon's Vegas Vacation. The Neon Boneyard is the perfect place to visit when you need a break from the flash of the Las Vegas Strip. It's an ideal stop for design and technology fans, too. The main museum explores how these two areas evolved over time through the medium of neon signage.

Renwick Smallpox Hospital

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Smallpox was said to have been eradicated in 1980, according to the Centers for Disease Control. An incredibly infectious disease, it can spread rapidly. In an attempt to curb its spread in the 19th century, officials established specially designated hospitals. And if you're feeling brave, you can still see the crumbling ruins of one of these hospitals today.

Located on Roosevelt Island in New York City, the Renwick Smallpox Hospital (now nicknamed The Ruin) was built in 1854 and abandoned in the 1950s. Despite the crumbling facade, it's a beautiful example of Gothic revival architecture.

However, there are rumors the abandoned hospital may not be quite as deserted as previously thought. Sightings of ghosts and unexplained phenomenon have been reported at the location. Night guards keep curious visitors away from the building, however. The building is fenced off to the public. Still, you can easily see the hospital from the road and main entrance. Great for ghost hunters and history buffs alike.

Museum of Death

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Fascinated by serial killers? Intrigued by the afterlife? Then, the Museum of Death in Los Angeles, California, is the place for you. Be forewarned, however: the museum's website claims that many visitors have fainted over the years. Make sure you prepare yourself for some of the more gruesome exhibits. These include crime scene photographs, serial killer artwork, pet taxidermy, and a large collection of coroner's instruments.

The museum isn't just for satisfying voyeuristic thrills. Founders JD Healy and Cathee Shultz wanted to educate visitors about death. They believed it was a subject that's too often considered taboo.

The founders encourage visitors to spend as long as they want looking at the hundreds of death-related items in the museum's collection. While it's not for everyone, it's an intriguing look at our relationship with death and how it affects those of us who are still living.