(CNN)When it comes to travel, most of us usually look for hotels that are conveniently located, affordable and comfortable.
12 unusual hotels you won't believe actually exist
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But sometimes, we want something out of the ordinary.
These 12 eccentric hotels highlighted by TripAdvisor provide an unforgettable sleep.
At first glance, this hotel appears to be made up of a series of houses stacked one on top of another.
Inspired by the architecture of traditional houses of the Zaan region, the green facade of Inntel Hotel Zaandam is eye-catching even from afar.
Located next to the Zaandam train station, it takes only 12 minutes to get to the Amsterdam city center.
Originally part of an Amsterdam shipyard that operated between 1894 and 1979, this historic crane has been transformed into a cool hotel.
The Faralda Crane Hotel is located at the top of the 50-meter-high structure and there are only three suites available for booking.
If staying atop a former industrial monument isn't exciting enough, you can rope-jump off the crane and free fall 164 feet.
Famous for its donut-like shape, the Sheraton Huzhou Hot Spring Resort in China offers amenities and services that are even more attractive than its architecture.
For one, there's an underwater bridge that connects the two towers of the hotel.
At night, there's a spectacular light show during which the building's distinctive structure is illuminated.
Built in the 1960s, this hotel looks more like something from a sci-fi movie than a place to spend the night.
Located 1,012 meters above sea level, Hotel Jested offers stunning panoramic views of the Czech Republic countryside.
According to the hotel's website, railings in the interior of the hotel are made of discarded pieces of steel that have been welded together, giving the place an industrial feel.
This one's definitely not for claustrophobics.
At 9 Hours Capsule Hotel Kyoto, you sleep alone inside a capsule.
Inside each sleeping pod is a sleep ambient control system, which claim to support sleep-wake rhythms to help you get a better rest.
Want to go on a cruise but afraid of getting seasick?
South Korea's Sun Cruise Resort may be your answer.
Calling itself the "first luxury cruise ship on land," the resort offers everything you'd experience on a luxury cruise ship -- except maybe seasickness.
There's even a rotating sky lounge offering great views of the ocean.
Spitbank Fort sits right in the middle of the sea.
With a distinctive circular concrete exterior, the English site has been transformed from a gun emplacement into a luxurious private island fitted with a rooftop pool, sauna and fire pit.
Oh, and there's one small thing that might add to the unique experience -- an alleged ghost resides at Spitbank Fort.
Located in Vancouver Island's coastal rainforest, Free Spirit Spheres are individual suspended spherical tree houses designed to allow guests to experience nature in a new way.
Three handcrafted spheres -- Eve, Eryn, Melody -- are available for overnight rentals.
Access to "rooms" involves strolling across elevated walkways and bridges and walking up spiral staircases.
No need to worry about missing your stop if you fall asleep on this train, because it doesn't actually move.
Owners Mike and Susan Wilson have renovated retired Alaska Railroad cars into a unique bed and breakfast known as The Aurora Express.
Each room is decorated with themes based on historical periods in Alaska.
The cars in the train sit permanently on 700 feet of railroad track that overlooks the Tanana River, mountains of the Alaskan Range and city of Fairbanks.
It might not be luxurious, but the Wigwam Motel offers individual teepees that are cozy and comfortable.
Influenced by Native American culture, Frank Redford began building these motels across America in the 1930s.
Only three remain today.
La Balade des Gnomes looks like an odd farmhouse, but it's actually an imaginative hotel with 10 guest rooms.
From the Trojan horse suite to the "sailboat" in its own pool, each room's design is inspired by a fairy tale.
This vintage 1965 Boeing 727 airframe is located in the jungle canopy of Costa Rica.
Hotel Costa Verde bought this retired aircraft and transported it from San Jose International Airport into the lush Manuel Antonio National Park.
It's been refurbished and transformed into a luxurious hotel suite that sits on a 50-foot pedestal.
At this height, guests can enjoy top ocean and jungle views.