From sprawling dams to airports to luxury hotel resorts, spectacular feats of engineering often come with a hefty price tag, especially for projects that see costs overrun during the construction process. Click or scroll through the top 30 most expensive structures ever built, adjusted for inflation and ranked by today’s US dollar.

This 101-storey residential tower is the third tallest in Dubai. There are several basement levels for car parking and eight retail units. Other amenities for residents include indoor and outdoor pools, gym facilities, a children’s play area, and a mosque. The construction cost of the building, which opened in 2012 after six years of construction, reached $2.17 billion (£1.7bn).

Earning the title of the world’s tallest building when it opened in Taiwan in 2004, Taipei 101 would soon be overtaken by the Burj Kalifa in Dubai in 2007. But this 101-storey building still reaches a pretty high 1,667 feet (508 metres). The soaring tower houses a shopping mall at its base, while office space makes up the rest. The building cost $1.8 billion, the equivalent of $2.4 billion (£1.8bn) in today's money. In 2011, the Taipei 101 was awarded the LEED Platinum Certification for energy efficiency and environmental design, due to its double-pane windows which block external heat, and other green features including a water recycling system.

Connecting Brooklyn and Staten Island in New York, USA, this was the world’s longest suspension bridge when it opened in 1964, until the Humber Bridge in England was built in 1981. The distance between its 693-foot (211m) tall towers is a span of 4,260 feet (1,299m). The 1964 construction price was $320 million, the equivalent of $2.7 billion (£2.1bn) in today's money.

One of many luxurious resort-and-casinos in Cotai, Macau, City of Dreams opened in 2009 and its form is based on a podium, boasting four towers. Built by Melco Crown Entertainment Ltd, the designers behind it include big names in architecture like Zaha Hadid Architects which worked on Morpheus, one of the complex's hotels. The facility also includes two theatres, 20 restaurants and four hotel towers. The casino alone accounts for 420,000 square feet (39,000 square metres). At the time of construction, costs totalled $2.4 billion, the equivalent of $2.9 billion (£2.2bn) in today's money.

Just across the street from City of Dreams in Macau, this resort is modelled on its sister property, the Venetian Las Vegas, which itself is inspired by the architecture of Venice, Italy. A total of 39 storeys and 10.5 million square feet (980,000 square metres), makes it one of the top 10 largest buildings in the world by floor area. The resort also boasts one of the largest casinos in the world at 550,000 square feet (51,000 square metres). In 2007, when it opened, construction costs reached $2.4 billion, the equivalent of $3 billion (£2.3bn) in today's money.

South Korea’s tallest building soars above the Seoul skyline, topping out at 1,821 feet (555m). At the time of opening, it was the fifth tallest tower in the world in 2017. With 123 storeys the mixed-use development opened not only to the usual offices and residences, but also a mall and a concert hall. Its swimming pool on the 85th floor and glass-bottom viewing deck are both the highest of such amenities in the world. 

An earthquake in 2001 showed the vulnerability of Seattle’s Alaskan Way Viaduct. The state opted to build a tunnel, 2 miles (3.2km) long and 53 feet (16.2m) in diameter, to replace the elevated highway along the city’s waterfront. When construction started in 2011 the tunnel boring machine held the record for the world’s largest diameter. Initially the tunnel was estimated to cost $3.3 billion (£2.5bn), however repairs and delays on the project, which opened in 2019, have driven up the cost. The final bill has yet to be revealed.

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When the Wynn opened in 2005 it was the tallest building in Las Vegas. Its 45 floors house more than 2,700 hotel rooms and the building also includes a convention centre, retail, and of course a casino. Once inside the resort guests see a spectacular curtain waterfall cascade into a three-acre-lake. Construction of the Wynn in 2005 cost $2.7 billion, the equivalent of $3.6 billion (£2.8bn) in today's money. 

The tallest building in the US opened in 2014 on the site of the rebuilt World Trade Center in New York. One WTC, sometimes called the Freedom Tower, is a total of 1,776 feet (541m) including its spire and has 104 floors. Initial plans estimated the cost of construction to be $3 billion, though that increased to $3.8 billion (£2.9bn) in 2012, making it the most expensive building in the world at that time. 

Built for the 1976 Summer Olympics, this is the largest stadium in Canada by seating capacity. Initial plans from 1970 estimated the construction at only CAD 134 million, however strikes and delays are said to have escalated these costs. When it opened in 1976 the total had skyrocketed to CAD 1.1 billion, the equivalent of CAD 5 billion ($3.8bn/£2.9bn) in today's money. The city’s Canadian football and baseball teams played at the stadium until 1998 and 2004 respectively, and while games are still sometimes played there no team has called it home since.

Las Vegas’ most expensive hotel and casino opened in 2010, comprising two towers both 603 feet (184m) tall, and 3,000 hotel rooms. Along with a 108,000 square-foot (10,000-square-metre) casino, guests have access to three different types of pools (including a nightclub pool), a spa and more than 215,000 square feet (20,000 square metres) of retail and restaurants. There’s also a 3,200-seat theatre, and a 60,000-square-foot (5,600-square-metre) nightclub and dayclub, as well as Rose. Rabbit. Lie. a modern supper club.

Compared to Las Vegas’ big resorts with their thousands of rooms, this Abu Dhabi hotel has just 300 rooms and suites spread over two wings. Luxury finishes are everywhere in the sprawling space, which covers 60 acres (24.3 hectares), from Swarovski crystal chandeliers to more than 150,000 cubic yards (115,000 cubic metres) of imported marble. When it opened in 2005 at a cost of $3 billion it was the world’s most expensive hotel; that's the equivalent of  $4 billion (£3.1bn). The building has recently had a change of management, and is set to be renovated over the next two years as it transitions to become a Mandarin Oriental property.

Located in Cotai, Macau, this 28-storey hotel is the second Wynn property in Macau, with the first – Wynn Macau – opening 10 years earlier in 2006. The Wynn Palace offers luxury suites and villas along with more than 1,000 hotel rooms. Its four penthouses each measure 3,900 square feet (360 square metres), and have two master bedrooms, walk-in closets, and grand pianos among other luxuries. The hotel’s exterior features a performance lake with light features, as well as a gondola-style cable car transportation system. The development stretches to a whopping 6 million square feet (557,000 square metres).

This 11 mile (18km)-long fixed link across the Storebælt strait (Great Belt in English) in Denmark comprises two bridges and a tunnel for both traffic and rail. The structure links the islands of Zealand and Funen. Construction work took about 10 years starting in 1988, and costs for the entire project totalled DKK 21.4 billion in 1988 prices, the equivalent of DKK 39.4 billion ($5.7bn/£4.4bn) in today's money.

Singapore is home to the world’s most unusual hotels. Opening in 2010, the 2,500-room hotel has two theatres, restaurants, shopping and other amenities including a casino. Its striking architecture by Moshe Safdie features three towers each 640 feet (195m) tall, connected by a 1,115 feet (340m) long rooftop terrace, designed to resemble a boat, which is home to the world's largest Infinity Pool. The total area of the building as a whole is a whopping 9 million square feet (845,000 square metres).

Designed for vehicle and rail traffic, this 9.9 mile (16km)-long link connects Sweden and Denmark. Construction included a bridge, a tunnel and an artificial island to connect the two. Work started in 1993 and the first passengers crossed in 2000. The cost at the time of completion was DKK 30.1 billion, the equivalent of DKK 41.3 billion ($6bn/£4.6bn) in today's money; it is expected to be paid off by 2037.

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Often called the Bay Bridge, a 1989 earthquake damaged both the east and west sections, of this San Francisco Bay structure, which meet at an island in the middle. While the west section could be repaired, the east needed to be replaced. After building the $6.4 billion (£4.9bn) new eastern span, which opened in 2013, crews carefully demolished the original structure, work that required three years and another $239 million (£183.1m).

When construction started on a new terminal at London’s Heathrow Airport in 2002 it was considered the largest construction project in Europe. Opening in 2008, the Terminal 5 project gave Heathrow airport an additional 3.8 million square feet (353,020 square metres) of terminal space, more than 100 shops and restaurants, and the capacity to handle 35 million passengers. It was solely dedicated to British Airways flights until 2012. The structure cost £4.3 billion to build, the equivalent of  £5.8 billion ($7.6bn) today. In 2018 Terminal 5 had a total of 32.8 million passengers. 

Even in the 19th century engineers studied tunnelling under the English Channel, but it would take more than a century to realise that dream. The 31 mile (50km)-long rail tunnel is the longest in the world under the sea. Built between 1987 and 1994, it actually consists of three tunnels: two for rail traffic and one for services. In total, the undersea megaproject cost £4.65 billion at the time of completion, which amounts to $12.2 billion (£9.3bn) in today’s money.

At 35 miles (57km) long, this is the world’s longest and deepest railway tunnel, comprising two twin tunnels constructed through the Alps in Switzerland. Construction started in 1999 using four tunnel boring machines to excavate the tunnels, and during the project nine workers died due to various accidents. The first train passed through in 2016 and both freight and passenger trains rely on the link.

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Opening in 2011 in Mecca, this seven-tower complex is owned by the Saudi government and houses luxury hotels, residences and a five-storey shopping mall. The building, which is part of the King Abdulaziz Endowment Project, is built on the ruins of the Ajyad Fortress and overlooks the world’s largest mosque and Islam’s most sacred site, to which Muslims pilgrimage annually. The 1,972 feet (601m)-tall central clock tower boasts the world’s largest clock face. 

Also known as “The Big Dig”, this Boston tunnel and bridge link is America's most expensive highway project. Originally scheduled to open in 1998, a series of delays and other problems plagued the project so that it was completely finished 15 years after construction started. Initial cost estimates in 1982 predicted a $2.8 billion price tag, but by the time work finished in 2007 those costs had overrun by 190%. The Boston Globe has estimated the cost including interest at $22 billion (£16.9bn) in total.

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At a total length of 34 miles (55km), this series of bridges, an undersea tunnel and four artificial islands connects three major cities in China's Pearl River Delta. It’s the world’s longest sea-crossing bridge and when it opened in 2018 the travel time between Zhuhai and Hong Kong dropped from about four hours to 30 minutes. The massive construction undertaking saw schedule delays and cost overruns, as well as hundreds of worker injuries, and at least 19 deaths.

With a total retail area of 5.4 million square feet (502,000 square metres), visitors can choose from more than 1,300 shops and 200 restaurants. The complex also offers an aquarium, virtual reality park, an Olympic-size ice rink, and a cinema, among other entertainment options. It’s one of the biggest malls in the world in terms of total facility space. First opening in 2009, the centre cost $20 billion at the time, the equivalent of $24 billion (£18.4bn) today. It saw 39 million visitors that year, and that number has since more than doubled; the shopping centre has taken the title of the most visited mall in the world.

Built on an artificial island 3 miles (5km) from Japan’s coast, construction started on Kansai International Airport in 1987, with the hope that it would relieve pressure on nearby Osaka International. In total three mountains were excavated for 21,000,000 cubic metres of fill, and 10,000 workers were needed to complete the 30m layer of earth built on the sea floor to create the island. Designed by Renzo Piano, the airport opened in 1994, at an initial cost of $14 billion, though by 2008 the price had risen to $20 billion. The cost is the equivalent of $24.3 billion (£18.5bn) in today's money.

With air traffic growing, as well as the city’s population, Hong Kong had no space to expand its original airport. But an engineering study found a solution by building another airport on the small Chek Lap Kok island. The construction work entailed enlarging the island with fill, much like Kansai Airport in Japan, and increased Hong Kong's land mass by 1%. The airport opened in 1998 at a cost of more than $20 billion, the equivalent of $31.5 billion (£24bn) in today's money. More than 71 million passengers travelled through Hong Kong’s airport in 2019, and it’s ranked the busiest cargo airport worldwide.

Construction started in 1994 on the world’s largest, and most expensive, hydroelectric dam, which is located on the Yangtze River, in China’s Hubei province. Aiming to introduce flood control to the region and provide power generation, the 605 feet (184m) tall and 7,600 feet (2,316m) long dam led to the relocation of 1.3 million people. In fact, construction submerged 13 cities, 140 towns and 1,350 villages. The dam's construction was completed in 2006, and went fully online in 2012. In 2009 China said that the project cost 254.2 billion yuan, the equivalent of 337.4 billion yuan ($48.3bn/£37bn) in today's money. 

Located on the Paraná River between Brazil and Paraguay, Itaipu provides 15% and 90% of each country’s energy consumption, respectively. Construction started in 1974 for the 643 feet (196m)-tall, 5 mile (8km)-long dam, and electricity generation followed a decade later in 1984. Although the Three Gorges in China is the larger facility, Itaipu's 20 turbine generators actually produce the most energy of any hydroelectric project in the world, creating around 98 trillion watt-hours a year. When completed construction costs reached $19.6 billion, the equivalent of $48.7 billion (£37.3bn) in today's money.

The world’s largest mosque and the site to which Muslims pilgrimage for Hajj, the Great Mosque of Mecca has existed for many centuries. Renovations have expanded its size and updated its building materials and interior finishes. The mosque covers 99 acres and can accommodate up to four million pilgrims during the Hajj. The total cost of construction and maintenance of the holy building has been estimated at an incredible $100 billion (£76.7bn).

Built to protect trade routes as well as property, the wall stretches over 13,171 miles (21,196km) and is more than 2,300 years old. Over the course of the project, it is estimated that millions of people helped to build the wall, with possibly as many as 400,000 dying during construction. There is debate over the construction cost, but it ranges from $95 billion (£73bn) to a higher estimate of $360 billion (£276bn).

The most expensive megaprojects ever