1. Dancing House; Prague, Czech Republic
Designed by Czech architect Vlado Milunić alongside the famed American architect Frank Gehry, Prague's Dancing House, nicknamed "Fred and Ginger" in honor of dancers Fred Astaire and Ginger Rogers, sits upon the banks of the Vltava River in the city center. Originally meant as an art gallery, the building was later bought by a financial services company.
2. Bubble House; Cannes, France
The Bubble House, or Palais Bulles, sits on the cliffs of France's Côte d'Azur, overlooking the Mediterranean Sea. The home was built in 1989, designed by architect Antti Lovag and purchased by fashion designer Pierre Cardin. Located in one of the most glamorous areas of France, the home is often rented out for parties or photo shoots.
3. Spittelau District Heating Plant; Vienna, Austria
This heating and waste incineration plant in the Austrian capital of Vienna is popular amongst photographers due to its irregular colors and shapes. Designed by Friedensreich Hundertwasser, the plant is a center for waste and recycling, as well as the generation of heat and hot water.
4. Crooked House; Sopot, Poland
The Crooked House, or Krzywy Domek in Polish, is a shopping center in the seaside town of Sopot. The building was designed by Szotyńscy & Zaleski, who were inspired by fairy tale illustrations to create the undulating shapes that comprise the final product.
5. Waldspirale; Darmstadt, Germany
This rainbow spiral of a building actually functions as an apartment complex in the German city of Darmstadt. The roof of the building is covered in grass, trees, and shrubs, and apparently some trees have even been known to protrude from the building's windows. Those windows, by the way, are all completely unique — all 1,000 of them.
6. Hang Nga Guesthouse; Dalat, Vietnam
Also referred to as the "Crazy House", the Hang Nga Guesthouse is a hotel built by architect Dang Viet Nga. Each room in the home has a different theme, although the overall impression the home gives is of a building melding into its natural surroundings.
7. Casa Milà; Barcelona, Spain
Known to many as La Pedrera (meaning "the stone quarry"), Casa Milà is one of architect Antoni Gaudí's signature creations in his beloved city of Barcelona. The building, a hallmark of Catalan architectural modernism, became a UNESCO World Heritage Site in 1984.
8. Hotel Galéria Spirit; Bratislava, Slovakia
What kind of looks like an explosion of colorful modern art is actually the Hotel Galéria Spirit in Bratislava, the capital of Slovakia, located right on the country's border with Austria. Not far from Old Town Bratislava, the hotel's unique look stands out amongst the rest of the city's buildings.
9. Upside Down House; Szymbark, Poland
Designed by businessman Daniel Czapiewski , the Upside Down House was originally meant to stand as an artwork reflecting the sense of uncertainty in the years following the end of the communist era. Visitors are able to enter the home and wander around, although many find the experience too disorienting.
10. Ideal Palace; Hauterives, France
The Ideal Palace was designed and created by Ferdinand Cheval, a postman in rural France. Construction began in 1879, but was not complete until 1912, 33 years later. In the late '60s, the palace was designated a historic monument by the Minister of Cultural Affairs.
11. Guggenheim Museum; Bilbao, Spain
Frank Gehry's Guggenheim Museum in Bilbao is perhaps one of the most well-known examples of contemporary architecture today. It's undulating facade was so complex to design that Gehry had to use a software system initially created for use in the aerospace industry.
12. Pabellón de Aragón; Zaragoza, Spain
This pavilion was designed to represent the Spanish region of Aragon, in which the city of Zaragoza is located, at the 2008 International Expo. The main structure is raised up on three pillars, leaving the space below open to be used during the event as a plaza and meeting space. The facade of the building is meant to evoke a wicker basket, with panels of glass and concrete intertwining to create that effect.
13. Hotel Marqués de Riscal; Elciego, Spain
Another Spanish stunner, another building designed by Frank Gehry. Opened in 2006, the Hotel Marqués de Riscal contains all of the signature elements of Gehry's design, with curving panels of metal adorning the outside and various tilts and zigzags throughout. The building has helped establish this area of Spain as a premier destination for wine lovers.
14. Selfridges Department Store; Birmingham, England
Designed by the architecture firm Future Systems, the Birmingham branch of the Selfridges Department Store is covered in 15,000 shiny aluminum discs, giving the building an almost alien-like sheen.
15. Fuji Television Building; Tokyo, Japan
Although it looks almost as if it were constructed by children using K'Nex or Lego blocks, the Fuji Television Building was in fact designed by Kenzo Tange Associates. At the top is a spherical observation tower that weighs over 1,300 tons and provides views of the city and Mount Fuji.
16. Kunsthaus; Graz, Austria
The Kunsthaus, meaning art museum, in the city of Graz is referred to by locals as the "Friendly Alien" due to its strange look. The museum, which houses contemporary works, is also a green building, with built-in photovoltaic panels on the roof allowing the building to generate its own power.
17. National Museum of the American Indian; Washington, D.C., United States
Part of the Smithsonian Institution, the National Museum of the American Indian sits on the National Mall in D.C. It was designed in collaboration with the Native American Design Collaborative, among other members of Native communities, in order to reflect the sensibilities of the various Native cultures that exist throughout America.