The World's 25 Most Impressive Megaprojects.

The biggest and boldest projects on the planet

Skyscrapers are reaching for new record heights, huge tunnels are establishing new transportation connections, and colossal bridges are spanning greater distances than ever before. Around the world, gigantic engineering and infrastructure projects are opening up or are closing in on their completion. So we surveyed those finished within the last three years and those under construction to find the most jaw-dropping dams, buildings, and big machines on Earth.

1). Panama Canal Expansion, Panama:-
  

Time to build: 11 years
Cost to build: $5.25 billion

The Panama Canal is so 1914. That's why the expansion project, set to complete in 2016, will carve out a new 3.8-mile-long channel for new locks—which require 4.4 million cubic meters of concrete—and widen and deepen what is already there. Ships have grown a lot over the past century, and so the world's most famous canal must do the same to keep pace, even if that does mean whittling away more of Panama.

2). Port Mann Bridge, Vancouver, B.C:-

Time to build: 6 years
Cost to build: $1.93 billion

The widest bridge in the world (until the Bay Bridge's east span recently opened), the bridge east of Vancouver, B.C., which opened in 2012, remains the second-longest bridge in North America. The cable-stay bridge uses an impressive 288 cables to reach a total bridge length of 6,866 feet.

3). Three Gorges Dam, China:-

Time to build: 17 years
Cost to build: $22 billion

We can't even comprehend the amount of concrete needed to construct the world's largest dam. Standing on China's Yangtze River, this 17-year, $59 billion project measures 595 feet tall, 131 feet wide, and more than 7,600 feet long, with 32 main turbines producing electricity.

4). One World Trade Center, New York:-

Time to build: 7 years
Cost to build: $3.8 billion

The tallest building in the Western Hemisphere rises a symbolic 1,776 feet above New York City. The largely steel structure also includes a concrete core that provides additional security and strength. It's almost as if there's a second skyscraper within the first.

5). Aizhai Suspension Bridge, China:-

Time to build: 5 years
Cost to build: $600 million

The world's highest bridge, connecting two tunnels in China, is also one of the world's longest suspension bridges. Opened in 2012, the bridge sits 1,200 feet over the Dehang Canyon and spans a tower-to-tower distance of 3,858 feet. The mountains on either side anchor the suspension towers.

6). Marmaray Tunnel, Turkey:-

Time to build: 9 years
Cost to build: $4.5 billion

It took nine years and $4.5 billion to build, but the 47-mile underwater railway tunnel connects the European and Asian sides of town, giving Istanbul a new rail line into and out of the city when it opened in 2013.

7). FFR Grand Stade, Paris:-

Time to build: 4 years
Cost to build: $552 million

Retractable roofs are nice. Retractable fields, too. Put them together and add 82,000 seats and the rugby federation of France will have a nearly mobile stadium on a giant scale located south of Paris. The two million-square-foot venue will become one of the largest stadiums in all of Europe, including serving as the largest roofed entertainment venue. And one of the most moving.

8). Jubail Industrial City, Saudi Arabia:-

Time to build: 10 years
Cost to build: $11 billion

The ongoing expansion of a city built from the sand up starting in the 1970s required plenty of logistical planning. The project, located in the Eastern Province of Saudi Arabia, is undergoing an $11 billion expansion to update all things industrial. The four-phase project over nearly eight square miles includes eight blocks of industrial plants, four blocks of petrochemical industry, three blocks of support industries and four blocks of aluminum and other smelting plants. And that doesn't even include removing hills, building tunnels, expanding fiberoptics, building highways and using seawater for daily cooling.

9). Liuchonghe Bridge, China:-

Opened in 2013 with a 1,437-foot span, the second-highest cable-stayed bridge in the world rises 1,100 feet above the Liuchonghe River. With one of the river canyon's walls acting as a virtual cliff and the two towers sitting above the canyon—one at 623 feet tall and the other 517 feet—you can expect some crazy views if you visit here.

10). London Crossrail, London:-

Time to build: 11 years
Cost to build: $23 billion

London continues to grow underground. Eight tunneling machines recently wrapped up 26 new miles of tunnel for new subway track that will connect 40 stations—including 10 completely new ones—to improve transportation in England's largest city.

11). Hyderabad Metro Rail, India:-

Time to build: 14 years
Cost to build: $2 billion

It will take all of the $2 billion-plus to create a new, elevated Hyderabad Metro Rail system in India. With initial phases nearing opening, the 46-mile light rail system will modernize an entire region. Elevated stations will appear every kilometer and are expected to handle 15 million riders, with trains arriving at stations every three to five minutes. With trains running at an average of over 20 miles per hour, all technology—track, stations and support—will run above ground.

12). Hong Kong-Zhuhai-Macao Bridge, China:-

Time to build: 7 years

Cost to build: $10.6 billion

The incredible scope of this mega-infrastructure project includes a 16-mile bridge-to-tunnel structure, with the tunnel portion spanning about four miles. Two artificial islands for the tunnel landings will help engineers create both the tunnel section and anchor the bridge portions, which will connect Hong Kong and the mainland via a mega-crossing.

13). Songjiang Hotel, China:-

Time to build: 2 years
Cost to build: $538 million

Don't mind the waterfall. It's a key feature of this hotel built into a 328-foot-tall quarry outside of Shanghai. The 19-story hotel will have the waterfall cascading down the middle and two hotel floors that are entirely underwater.

14). Russky Bridge, Russia:-

Time to build: 4 years
Cost to build: $1 billion

At a total length of over 10,000 feet, the $1 billion Russky Bridge in southwestern Russia became the world's longest cable-stayed bridge when it opened in 2012. The 168 cable stays from its towers support the load of the bridge, and pylons standing more than 1,000 feet high anchor the cables. Just the middle channel of this three-segment bridge is about the length of the Golden Gate Bridge. The longest cables stretch nearly 2,000 feet.

15). Etihad Rail, United Arab Emirates:-

Time to build: Unknown
Cost to build: $11 billion

Rail may soon be the fastest and easiest way to get around the United Arab Emirates. The three-phased Etihad Rail project, which now has the first phase wrapped, plans to connect 745 miles of new rail across the country to link with Saudi Arabia, Qatar, Oman, Bahrain, and Kuwait.

16). Al Maktoum International Airport, Dubai:-

Time to build: Estimated: 20 years
Cost to build: $31 billion

The original opening in 2010 was never meant to be the final word on the new airport for Dubai. Al Maktoum will receive a $32 billion expansion set to last up to eight years that will allow for 220 million passengers per year to fly out of the desert. The shear scope of an airport spread over 21 square miles will accommodate 100 Airbus A380 aircrafts at any given time.

17). Beijing Daxing International Airport, China:-

Time to build: 5 years
Cost to build: $13 billion

This will be the home of the world's largest airport terminal, the gleaming Terminal 1, designed by Zaha Hadid. Built to accommodate 100 million passengers per year and with seven runways and 7.5 million square feet of the space, the airport's first phase should finish in 2018, with the rest slated to wrap up in 2025.

18). Bertha Tunnel-Boring Machine, Seattle:-

Time to build: 2 years
Cost to build: $80 million

While Bertha hasn't moved forward since it got stuck underground in December 2013, the world's largest tunnel-boring machine, at 57.5 feet in diameter, is undergoing repairs that should have it churning dirt again this fall. The 7,000-ton, 326-foot-long machine needed even more robust power to make it all the way under downtown Seattle as it digs a new transportation artery.

19). New Century Global Centre, China:-

Time to build: 3 years
Cost to build: Unavailable

At more than 18 million square feet, the New Century Global Centre is the world's largest freestanding building in terms of floor space. The structure includes multiple shopping malls, hotels, offices, theatres, theme-park-like attractions, and even a water park.

20). Atlanta Falcons Stadium, Atlanta:-

Time to build: 3 years
Cost to build: $1.2 billion

Any new football stadium is probably going to get a retractable roof. This $1.2 billion altar to opulence, however, has one that's rather unusual: It's made of eight roof "petals" that create a camera lens-like effect when the roof opens and closes. Made of ETFE fabric, the translucent panels allow light into the stadium even when they're closed. The roof will take eight minutes to open and expose the brand-new stadium planned for a 2017 opening.

21). Shanghai Tower, China:-

Time to build: 8 years
Cost to build: $2.4 billion

When the world's second-tallest building opens, probably later this year, stacked steel plates will create a "tuned-mass damper" at the top of Shanghai Tower to protect it against swaying. At 2,073 feet tall, there's plenty of room inside the tower for offices, hotel rooms and public space. The 21 sky lobbies should also offer plenty of mind-blowing views.

22). Bay Bridge Eastern Span, San Francisco-Oakland:-

Time to build: 12 years
Cost to build: $6.4 billion

The world's longest self-anchored suspension bridge, thanks to its 2,047-foot main span, is also the world's widest bridge. A single 2.6-foot-diameter main cable loops around the roadway, held aloft on a 525-foot tower that supports 90 percent of the bridge's weight.

23). State Route 520 Floating Bridge, Seattle:-

Time to build: 5 years
Cost to build: $2 billion

Concrete floats quite nicely in Seattle, where engineers have devised a 7,710-foot-long floating bridge, the longest in the world. The new State Route 520 bridge will replace the current world's longest on a stretch of highway that floats across Lake Washington, connecting Seattle to points east. The new structure, rising 20 feet above the water, will open to traffic in spring 2016.

24). Skytree, Tokyo:-

Time to build: 4 years
Cost to build: $806 million

The world's tallest "tower" in the world (Burj Khalifa remains the world's tallest building) opened in 2012 in Tokyo. Standing 2,080 feet, the $1.8 billion tower has six TV transmission antennas has two observation decks for panoramic views, allowing tourists to survey Japan's capital city from 1,148 feet and 1,476 feet up.

25). Silver Line, Washington, D.C:-

Time to build: 8 years
Cost to build: $6.8 billion

The D.C. Metro is adding a color. The new silver line required 11.7 miles of new track and five new stations for the completion of phase one, which opened in 2014. Work has already started on phase two, which will add another 11.4 miles of track and six new stations, including a much-needed connection to notoriously difficult-to-reach Washington Dulles International Airport. The silver line has been noted as one of the most complex transportation projects in the country, as engineers had to plan and build amidst the already developed region.