Among the run of the mill skyscrapers and office centres, there are many amazing and extraordinary projects. This article by Tranio.com writer Julia Guschina brings you on a tour of the most unusual commercial buildings around the globe.

1. Apple HQ (Silicon Valley, USA)

By 2017, the construction of Apple's space-age headquarters in Cupertino will be completed. It might not be finished yet, but it has already earned a few affectionate nicknames like the "spaceship", "flying saucer" and "frisbee". According to Tim Cook, Apple CEO, it will be the world's greenest building and run exclusively on renewable energy.

The project will cost this IT-giant almost $5 billion, making it the world's most expensive commercial construction ever, even more expensive than the One World Trade Center in New York (only $3.9 billion). True to Silicon Valley style, the 260,000 sq m campus will include jogging paths, walking trails and cafes nestled in among the 7,000 trees that are being planted as well as an auditorium accommodating 1,000 people, underground parking and enough space to house 13,000 employees.

2. Nakagin Capsule Tower (Tokyo, Japan)

The Nakagin Capsule Tower was designed by architect Kisho Kurokawa in 1972. The latter was a founder of Metabolist Movement, an architectural school that combines notions of organic biological growth into the design of megastructures.

This 13-floor tower was built with 140 capsule modules measuring 2.3 x 3.8 x 2.1 metres, all of which are detachable and easy to replace (though this has not actually been tried as of yet). Today the tower is a residential and office building as well as a tourist attraction. It is on the list of world architectural heritage of DOCOMOMO International.

3. NORD/LB Bank HQ (Hannover, Germany)

Hannover's main tourist attraction is the headquarters of NORD/LB Bank, a futuristic building made of glass and steel blocks connected by transparent corridors. It is even equipped with three artificial lakes covering 300 sq m of its territory.

After completion in 2002, it won the prestigious British Stirling Prize for original architectural design. This unique skyscraper accommodates 1,500 employees as well as a restaurant and an art gallery. At night, it turns into a futuristic fairy-tale castle illuminated by thousands of lights.

4. Robot Building (Bangkok, Thailand)

The Robot Building in Bangkok, designed by architect Sumet Jumsai, is supposed to reflect the modernisation and computerisation of society and comes complete with eyes and even antennae. Built in 1972, it serves as a headquarters for the United Overseas Bank located in the Sathorn business district.

This famous Thai "robot" is very popular with tourists, though few know that Jumsai actually got his inspiration whilst playing with his son's toys. Some say that it is an absurd construction, but it certainly has its charm. The Robot Building was named one of the most unusual buildings of the century by the Museum of Contemporary Art in Los Angeles.

5. ING House (Amsterdam, the Netherlands)

This quirky construction in the Dutch capital of Amsterdam is often referred to as "the Dustbuster" or "the Shoe", though it's really called the ING House, after the bank that built it (but is no longer there). It may be the most expensive construction in the Netherlands but some locals still can't agree on what it actually looks like. Is it a shoe? A boot? An ice-skate? No, it's the ING House...

The building's design was ruled by considerations such as the environmental footprint, open spaces and innovation. Aside from offices, there are six themed gardens, fountains, recreational zones and double soundproofing to insulate its occupants from passing cars on the nearby highway.

6. Kingdom Centre (Riyadh, Saudi Arabia)

Saudi Arabia's Kingdom Centre, also known as the Burj Al Mamlakah was opened in 2002. "The Bottle Opener", as some call it, can be recognised by its unusual design and large hole at the top. It is the third tallest skyscraper in the country.

The building has a mall, a five-star hotel, apartments and 3,000 parking spots as well as a mosque and a "Sky bridge" viewing point. The whole 297-metre construction cost Prince Al-Waleed €385 million, but also earned him a spot in the world's 50 tallest buildings.

7. Leaning Tower (Abu Dhabi, UAE)

Capital Gate, or the "Leaning Tower", is located in Abu Dhabi. The distinct curve in the building's design got it into the Guinness Book of Records as the "world's furthest leaning man-made tower", the angle of which (18°) is 4.5 times stronger than Italy's famous Leaning Tower of Pisa. It measures 165 metres, divided into 35 floors.

The first 12 floors of Capital Gate are vertical while the rest are tilted from 30 to 140 cm. It took four years to build and cost more than $2 billion. Offices occupy the building's lower levels and there is a five-star Hyatt Capital Gate hotel at the top.

8. Gate of Europe (Madrid, Spain)

The "Gate of Europe" (Puerta De Europa) is composed of twin buildings located in the heart of Madrid on Castilla Square (Plaza de Castilla). The towers were completed in 1996 according to a design by American architects Philip Johnson and John Burgee. Rumour has it that Johnson said: "We have to end the right angle if we do not want to die of boredom. The skyscraper is over; we can forget it".

True to form, Phillip and Burgee gave both towers a 15° incline so it looks like they are falling towards each other. The towers measure 155 metres shared over 26 floors. It is the second highest building in Spain right after the Torres de Santa Cruz residence buildings in the Canary Islands.

9. Aqua Tower (Chicago, USA)

Chicago's Aqua Tower measures 262 metres, making it the highest building in the world to be designed by a female architect. The façade of the building is truly unique, designed to emulate the surface of a waterfall. The architect, Jeanne Gang, says that she was inspired the limestone folds in the Great Lakes area.

The appearance is not only eye-catching, it's functional too: the horizontal panels block direct sunlight and protect from strong winds. There are 82 floors in total, the first 18 are occupied by a hotel, the rest by offices and apartments. Moreover, the roof has a massive park with running tracks, gazebos, hot tubs, a swimming pool and fire pits.

10. F&F Tower (Panama City, Panama)

The F&F Tower, previously known as Revolution Tower, is an office centre located in the financial district in the centre Panama City. This helix-shaped building is 243 metres high with each of its 39 top floors (of the 52) turned at an 9º against the previous one.

Bright sparkling turquoise and emerald colours make the tower even more noticeable among neighbouring grey skyscrapers. In 2011, the F&F Tower won the world's most prestigious architectural prize: the Emporis Skyscraper Award for architectural excellence and functionality.

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