Story highlights
- The 555-meter-tall Lotte World Tower opens setting world records.
- The Lotte World Tower double-decker elevator travels at 10 meters per second, making it the fastest of its kind in the world.
- The Shanghai Tower's elevator is currently the world's fastest elevator, traveling at 20.5 meters per second.
- Experts say the fastest elevator humanly possible would travel at 24 meters per second.
(CNN)After six years of construction, the 555-meter-tall (1,820 ft) Lotte World Tower opened in April, setting three world records and redefining the Seoul skyline.
Not only is it the tallest tower in South Korea and fifth highest in the world -- dwarfing the Korean capital's next highest building, Three IFC Office Tower, by nearly 300 meters -- it's also home to the highest glass-bottom observatory at 478 meters (1,568 ft).
But its most impressive feat?
The Lotte World Tower features the world's tallest and fastest double-decker elevator, the Sky Shuttle, which whisks passengers from the basement to the 121st-floor observation deck in one minute, or at 10 meters per second.
From the top of the half kilometer-tall tower, visitors can survey the edges of Seoul's vast urban sprawl and the mountainous terrain beyond -- only a handful of other skyscrapers in sight.
Elevated design
Lotte hired American elevator manufacturer the Otis Elevator Company to bring its double-deck Sky Shuttle to life.
Lotte World Tower, Seoul
Consisting of two attached cabins stacked on top of each other, it simultaneously carries passengers to separate floors. Other famous structures featuring this type of technology include the Canton Tower, in Guangzhou; the Petronas Towers, in Kuala Lumpur; the Eiffel Tower, in Paris; and the Burj Khalifa, in Dubai.
Boasting twice the capacity of a conventional elevator -- each cabin holds 52 passengers -- the tower's lift directly connects the basement and the observation deck, skipping the floors in between which are full of shopping complexes, offices, and even a "seven star" hotel.
"A double-deck elevator was used because the observatory would be crowded at certain times of day," Wonixuk Choi, manager of Lotte Corporation, tells CNN.
Inside the lift cabins, it feels like a video game -- 15 OLED displays offer a virtual tour of Seoul during the 60-second ride.
Elevating Asia
Photos: The world's tallest buildings
Lotte World Tower, Seoul, South Korea – Opened in April 2017, the Lotte World Tower is Seoul's first supertall skyscraper, and is currently the fifth tallest building in the world.
Height: 556 meters (1824 feet)
Architect: Kohn Pedersen Fox Associates
Height: 556 meters (1824 feet)
Architect: Kohn Pedersen Fox Associates
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Photos: The world's tallest buildings
The Tower, Dubai, United Arab Emirates – A new mega-tall skyscraper aims to be the tallest in the world, upon completion in 2020. "The Tower" will be built on the Dubai Creek Harbor, a massive new tourism development. The Tower will eclipse the Dubai's Burj Khalifa -- currently the tallest building in the world.
Height: 928m (3,044ft)
Architect: Santiago Calatrava
Height: 928m (3,044ft)
Architect: Santiago Calatrava
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Photos: The world's tallest buildings
The Tower, Dubai, UAE – The expected completion date for The Tower in Dubai is 2020.
Height: 928m (3,044ft)
Architect: Santiago Calatrava
Height: 928m (3,044ft)
Architect: Santiago Calatrava
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Photos: The world's tallest buildings
The Tower, Dubai, UAE – The building will hold several observation decks in its oval-shaped peak. One deck will offer a 360-degree view of the city.
Height: 928m (3,044ft)
Architect: Santiago Calatrava
Height: 928m (3,044ft)
Architect: Santiago Calatrava
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Photos: The world's tallest buildings
Jeddah Tower, Saudi Arabia – A threat to The Tower's tallest tower ambitions is the Jeddah Tower in Saudi Arabia. This tower is currently under construction and due to top out at 1km at a cost of $1.23 billion.
Height: 3,280ft
Architect: Adrian Smith + Gordon Gill Architecture
Height: 3,280ft
Architect: Adrian Smith + Gordon Gill Architecture
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Photos: The world's tallest buildings
The Burj Khalifa, Dubai, UAE – Currently world's tallest building, since it was completed in 2010, is the Burj Khalifa. It stands a massive 198 meters (650 feet) above its nearest competitor.
Height: 828m (2717ft)
Floors: 163
Architect: Skidmore, Owings & Merrill
Height: 828m (2717ft)
Floors: 163
Architect: Skidmore, Owings & Merrill
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Photos: The world's tallest buildings
Mecca Royal Clock Tower Hotel, Mecca, Saudi Arabia – Situated close to the Grand Mosque of the holy city of Mecca, the tower complex is one part of the $15 billion King Abdulaziz Endowment Project, seeking to modernize Mecca and accommodate the ever-growing number of pilgrims.
Height: 601m (1972ft)
Floors: 120
Architect: Dar Al-Handasah Architects
Height: 601m (1972ft)
Floors: 120
Architect: Dar Al-Handasah Architects
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Photos: The world's tallest buildings
One Vanderbilt Avenue, New York – A new tall tower has broken ground in New York City. Named the One Vanderbilt Avenue tower, the building is designed by Kohn Pedersen Fox architects, and construction officially started today. At 1,401 feet tall, upon completion it will be the second tallest building in New York after the One World Trade Center.
Height: 427m (1,401ft)
Architect: Kohn Pedersen Fox
Height: 427m (1,401ft)
Architect: Kohn Pedersen Fox
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Photos: The world's tallest buildings
Sky Mile Tower, Tokyo, Japan – In February, a proposal for a mile-high tower in Tokyo was revealed.
Height: 1,600m (5,250ft)
Architect: Kohn Pefersen Fox Associates and Leslie E Robertson Associates
Height: 1,600m (5,250ft)
Architect: Kohn Pefersen Fox Associates and Leslie E Robertson Associates
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Photos: The world's tallest buildings
Sky Mile Tower, Tokyo, Japan – The 1,600 meter tower is part of a future city concept named "Next Tokyo 2045," which envisions a floating mega-city in Tokyo Bay.
Height: 1,600m (5,250ft)
Architect: Kohn Pefersen Fox Associates and Leslie E Robertson Associates
Height: 1,600m (5,250ft)
Architect: Kohn Pefersen Fox Associates and Leslie E Robertson Associates
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Photos: The world's tallest buildings
1 Undershaft, London, UK – In December 2015, plans were unveiled for the 1 Undershaft -- a 300m tall building that could become the City of London's tallest building.
Height: 300m (984ft)
Floors: 73
Architect: Aroland Holdings
Height: 300m (984ft)
Floors: 73
Architect: Aroland Holdings
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Photos: The world's tallest buildings
1 Undershaft, London, UK – 1 Undershaft will sit across the river from London's tallest building, The Shard, which is 9.6 meters taller.
Height: 300m (984ft)
Floors: 73
Architect: Aroland Holdings
Height: 300m (984ft)
Floors: 73
Architect: Aroland Holdings
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Photos: The world's tallest buildings
432 Park Avenue, New York, U.S. – 432 Park Avenue, the tallest all-residential tower in the western hemisphere, opened its doors in December 2015, recently became the hundredth supertall building in the world.
Height: 425.5m (1396ft)
Floors: 85
Architect: Rafael Vinoly, SLCE Architects, LLP
Height: 425.5m (1396ft)
Floors: 85
Architect: Rafael Vinoly, SLCE Architects, LLP
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Photos: The world's tallest buildings
Shanghai Tower, Shanghai, China – Completed in 2015, Asia's tallest building surpasses the Shanghai World Financial Center and the Jin Mao Tower in Shanghai's Pudong district. Estimated to cost $2.4 billion, its completion marked the end of a project in the financial district stretching back to 1993.
Height: 632m (2073ft)
Floors: 128
Architect: Jun Xia, Gensler
Height: 632m (2073ft)
Floors: 128
Architect: Jun Xia, Gensler
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Photos: The world's tallest buildings
One World Trade Center, New York, U.S. – Known as the "Freedom Tower," One World Trade Center stands on part of the site previously occupied by the Twin Towers. It's the highest building in the western hemisphere, and cost $3.9 billion according to Forbes.
Height: 541.3m (1776 ft)
Floors: 94
Architect: Skidmore, Owings & Merrill
Height: 541.3m (1776 ft)
Floors: 94
Architect: Skidmore, Owings & Merrill
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Photos: The world's tallest buildings
Taipei 101, Taipei, Taiwan – The first skyscraper to break the half-kilometer mark, the world's tallest building between March 2004 and March 2010 is also one of the greenest -- certified LEED platinum in 2011. Designed to withstand the elements, including typhoons, earthquakes and 216 km/h winds, Taipei 101 utilizes a 660-tonne mass damper ball suspended from the 92nd floor, which sways to offset the movement of the building.
Height: 508m (1667ft)
Floors: 101
Architect: C.Y. Lee & Partners
Height: 508m (1667ft)
Floors: 101
Architect: C.Y. Lee & Partners
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Photos: The world's tallest buildings
Shanghai World Financial Center, Shanghai, China – Construction of Shanghai's third supertall building took 11 years, but the skyscraper dubbed "The Bottle Opener" was met with critical praise and high-end residents when it completed in 2008, including the Park Hyatt Shanghai and offices for Ernst & Young, Morgan Stanley, and BNP Paribas.
Height: 492m (1614.17ft)
Floors: 101
Architect: Kohn Pederson Fox
Height: 492m (1614.17ft)
Floors: 101
Architect: Kohn Pederson Fox
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Photos: The world's tallest buildings
International Commerce Center, Hong Kong, China – Hong Kong's tallest building has 108 floors -- but walking around it, you'd get a different story. The city's tetraphobia -- the fear of the number four -- means floors with the number have been skipped, and the International Commerce Center is marketed as a 118-story skyscraper.
Height: 484m (1588ft)
Floors: 108
Architect: Kohn Pedersen Fox
Height: 484m (1588ft)
Floors: 108
Architect: Kohn Pedersen Fox
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Photos: The world's tallest buildings
Shanghai Tower – Standing at 2,074 feet (632 meters) tall, the Shanghai Tower is the world's second tallest building.
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Photos: The world's tallest buildings
Petronas Towers 1 and 2, Kuala Lumpur, Malaysia – The joint eighth highest completed skyscraper is still the tallest twin towers in the world. Finished in 1996 and inaugurated in 1999, it's been the site of numerous hair-raising stunts. Felix Baumgartner set a then-BASE jump world record in 1999 by jumping off a window cleaning crane, and in 2009 Frenchman Alain Robert, known as "Spiderman," freeclimbed to the top of Tower Two without safety equipment -- and did so in under two hours.
Height: 451.9m (1483ft)
Floors: 88
Architect: Cesar Pelli
Height: 451.9m (1483ft)
Floors: 88
Architect: Cesar Pelli
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Photos: The world's tallest buildings
Zifeng Tower, Nanjing, China – The architects behind the Burj Khalifa are also responsible for the world's tenth tallest building. Skidmore, Owings & Merrill's Zifeng Tower in Nanjing completed in January 2010 and sits just above the Willis Tower (previously the Sears Tower) in the rankings, eclipsing the SOM-designed Chicago icon by a mere 7.9 meters (26 ft).
Height: 450m (1476ft)
Floors: 66
Architect: Skidmore, Owings & Merrill
Height: 450m (1476ft)
Floors: 66
Architect: Skidmore, Owings & Merrill
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Photos: The world's tallest buildings
Changsha IFS Tower, Changsha, China – A hotel and office hybrid, this straightforward supertall building by Wong Tung & Partners in Hunan Province's booming capital city is expected to be completed by 2017.
Height: 452 metres (1,482 ft)
Architect: Wong Tung & Partners
Height: 452 metres (1,482 ft)
Architect: Wong Tung & Partners
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Photos: The world's tallest buildings
Suzhou IFS, Suzhou, China – The Suzhou IFS is two meters shy of the Changsha tower.
Height: 450 meters (1476 feet)
Architect: Kohn Pedersen Fox Associates
Height: 450 meters (1476 feet)
Architect: Kohn Pedersen Fox Associates
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Photos: The world's tallest buildings
World One, Mumbai, India – The World One skyscraper in Mumbai will be as tall as the Willis Tower, the second tallest building in North America, and will be one of the world's tallest residential structures.
Height: 442 meters (1450 feet)
Architect: Pei Cobb Freed & Partners
Height: 442 meters (1450 feet)
Architect: Pei Cobb Freed & Partners
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Photos: The world's tallest buildings
Nanning Logan Century 1, Nanning, China – This design mimics and simplifies the neo-Gothic spires of an earlier skyscraper boom, à la the Woolworth and Empire State Buildings.
Height: 383 meters (1,257 ft)
Architect: Dennis Lau & Ng Chun Man Architects & Engineers
Height: 383 meters (1,257 ft)
Architect: Dennis Lau & Ng Chun Man Architects & Engineers
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Photos: The world's tallest buildings
Three Sixty West Tower B, Mumbai, India – Kohn Pedersen Fox is back with this 90-story residential building. Zigzagging cuts in the curtain-wall break up the monotony of yet another boxy tower.
Height: 372 metres (1,220 ft)
Architect: Kohn Pedersen Fox
Height: 372 metres (1,220 ft)
Architect: Kohn Pedersen Fox
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Asia has made a name for itself in ground-breaking elevator technology in recent years.
In 2016, the Shanghai Tower opened, unveiling the fastest elevator in the world.
The Mitsubishi-designed lift runs at an incredible 20.5 meters per second (67 ft/s).
Standing at 2,074 feet (632 meters) tall, a fast lift was always going to be necessary for the world's second tallest tower.
Also in China, Hitachi last summer unveiled the world's second fastest elevator in Guangzhou's tower CTF, which stands at 1,739 feet tall.
Its lift zooms from floors zero to 95 in an incredible 45 seconds -- or 20 meters per second (65 ft/s).
Inside the elevator cabin, an indicator shows passengers how fast they are going, perhaps to prove that they aren't being cheated.
Inside the world's second fastest elevator. 03:20
A high-tech air pressure adjustment system that protects ears from popping and blocks any uncomfortable G-force backlash means this lift is so smooth it's hard to believe it's the world's second fastest.
"The elevatoring strategy required us to bring in high volumes of people ... and the client made a huge investment to try to make sure that happened quickly, "Forth Bagley, principal architect at KPF, which designed the CTF tower, tells CNN.
Lift me up
Getting people around ever-taller towers with increasing efficiency is a common concern.
Reaching 1km into the sky, the Jeddah Tower in Saudi Arabia will be the world's tallest building when completed in 2019.
A building so tall, naturally, requires an exceptionally fast elevator.
The CTF Tower in Zhujiang New Town in Guangzhou, Southern China.
Finnish maker Kone has risen to the challenge, developing the "ultrarope" elevator, which uses a carbon-fibre cable strong enough to power a lift more than 1km in length -- previously, about 500km was the maximum length possible for a lift cable.
One third of the weight of traditional lift ropes, it also makes super speeds a reality.
The ultrarope lift will travel at "over 33 feet per second", and "reach the highest liveable floor in the world in 52 seconds," according to Kone.
When finally unveiled, it could easily be faster than Lotte World Tower's creation. However Albert So, an expert in elevator engineering, believes lift technology can't get much faster.
"I predict the maximum speed of a vertical lift cabin cannot be more than 79 feet per second," he says. "This is not because we can't make lifts that go faster than this, but because of the air pressure."
If a lift traveled faster than this, he says, it wouldn't give passengers enough time to acclimatize to the air pressure on the top floor.
Engineers would need to pressurize the entire building, like an airplane cabin.
Lifts that move sideways?
Perhaps the most exciting innovation in lift technology is coming from German transport firm Thyssenkrupp.
By using magnetic levitation, or "maglev" technology -- which uses magnetic fields rather than elevator cables to propel cabins -- the company is proposing elevators that move both vertically and horizontally.
Photos: Timber and bamboo -- wooden buildings are branching out
Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – This floating wooden pavilion is the Pavillion of Reflections in Zurich. It was revealed as part of Manifesta, an annual contemporary art biennial.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The wooden structure is a collaborative project between 30 architecture students from ETH in Zurich and design firm Studio Tom Emerson.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – Described as an "urban island," the floating structure is intended for leisurely use, and features an open-air cinema.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The "Sida Vid Sida" ("side by side") building is a proposed project by Swedish architects White Arkitekter.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The proposed design won an architecture competition in the city of Skelleftea. There were 55 entries from 10 countries.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The design was selected for its use of wood as a building material, as it pays tribute to Skelletea's rich local timber industry.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The building is expected to be completed in 2019.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – Oakwood Tower is a proposed structure by PLP Architecture and Cambridge University's Department of Architecture.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – At 80 stories high, it would be London's first wooden skyscraper, and another addition to the growing trend for structures made entirely of timber.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The Forte in Melbourne was completed in 2012, and is a 10-story structure built entirely of wood.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – For two years, the 104-foot tall structure was the tallest wooden building in the world.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – That title was soon taken by the Treet in Norway.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – Treet was completed in 2014, and is 14 stories tall.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The Wood Innovation and Design Center (WIDC) is located in the province of British Columbia in Canada.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – The building is a hub for wooden design education and research.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – In Bali, the 18-home Green Village is constructed almost entirely of bamboo.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – "This is the future. It's pure architecture ... to breathe fresh air and touch nature, that's everything," says architect Defit Wijaya.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – CRG Architects proposed a skyscraper made entirely of bamboo at the World Architecture Festival in 2015.
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Photos: Timber and bamboo -- wooden buildings are branching out
Wooden skyscrapers – Bamboo was recently recognized by the United Nations as a green building material that can help combat climate change.
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This type of elevator would be slower, at least initially, but it could increase travel efficiency throughout a sprawling building.
"I think this is our future," says So. "Our elevators will become more like a chess board, the pieces on the board moving around the building."
So acknowledges that governments around the world remain unconvinced of horizontal elevators' safety credentials, but says their introduction is only a matter of time.
"There is no practical value of building tall, when a tall building becomes slimmer as it gets taller," So says. "Most of the area at the top of the building is used for the elevator."
A bigger building with a horizontal elevator is a better use of space, he says.
