Montreal’s ‘Big O’ stadium was quickly renamed the ‘Big Owe’ due to the building coming in at 13 times the original cost estimate. There was a manic scramble to get it finished in time for the Games on 17 July 1976, with 3,000 staff working 24 hours a day in the final months, and even then it wasn't quite finished in time. Construction workers still finishing up reportedly got in the way of the first athletes coming into the stadium for the opening ceremony.

During the build, architect Roger Taillibert and Montreal's mayor Jean Drapeau, who had commissioned the stadium, faced multiple major obstacles. There were several labour strikes that wiped 30% off the available work time, a tripling of the price of structural steel to contend with, as well as corruption among officials. Three decades later, CBC reported that the $1.5 billion debt – the equivalent of $6.8 billion (£5bn) in today’s money – from the 1976 Summer Games had finally been cleared. However, despite having been used as a COVID-19 vaccination centre, it still remains something of a white elephant.

In 1990 the legendary Hubble Space Telescope was launched into orbit, 353 miles (568km) above Earth. At the time, the BBC reported how the Hubble would provoke “a drastic revision of the shapes, sizes and content of galaxies” – having already drastically revised its budget and deadline for launch. The Hubble took 20 years to build, which was at least seven years longer than planned. Plus, it cost three times the original estimate, coming in at $1.5 billion at the time, which is the equivalent of $2.9 billion (£2.4bn) in today's money.

Despite the cost, technical problems materialised even after the launch, including the malfunctioning of the solar panels that powered the telescope and flaws in the mirrors that help produce images. On Christmas Day last year, NASA launched the Hubble's successor: a new and improved, long-distance, high-resolution space telescope called the James Webb Space Telescope. However, the project has followed in its predecessor’s footsteps. After being announced in 1996, it was originally set to launch in 2007 at a cost of $1 billion. The cost later mushroomed to $8.8 billion (£6.5bn), with its launch date rescheduled twice as a result of the coronavirus pandemic.

When Denver’s new airport was finally complete, 16 months late, in 1995 it was hailed as an economic catalyst by advocates and a legally dubious, colossal waste of money by critics. The New York Times reported that the project had cost $4.9 billion by its completion, equivalent to $8.2 billion (£6.8bn) in today's money. This made it three times over budget, which led to the project's own financers filing suits. 

Multiple setbacks to planning and construction were responsible for the enormous overspends. Perhaps the single most costly failure was, ironically, the airport’s key selling point – an ultra-modern, fully-automated baggage system. It initially malfunctioned and shredded bags, and cost more than $100 million – equivalent to $397 million (£289m) today – to get into working order. Since then, the airport has been the subject of a host of conspiracy theories, from the hypothesis that markings on the airport floor are satanic symbols, to the idea that its underground bunkers might be a secret lair.

The megaproject didn't commence until the late 1980s with protests, environmental complaints and legal challenges significantly delaying its completion. Costing a budget-busting $1.3 billion, which is equivalent to $2 billion (£1.7bn) today, the highway eventually opened in 1997, but to this day local opposition remains strong and many Native Hawaiians refuse to use it as they believe it's cursed. The 15-mile freeway was shut for several days in September 2021 as the stretch was transformed into a mass testing site for COVID-19, but even this was controversial as local highway authorities objected to the road being used for this purpose.

The Three Gorges Dam on the Yangtze River, China was first proposed in 1919 by politician Sun Yat-Sen. But it wasn’t until the mid-1950s that the idea was given serious attention, and due to the Chinese civil war building work didn’t start until 1994. The largest hydroelectric power plant in the world, it was built by 40,000 workers over the course of 12 years. The dam was the subject of social media rumours last year, with images circulating that showed the dam apparently at risk of collapse and cities overcome with flooding, but officials denied the claims.

Designed by Spanish architect Enric Miralles, the project was rife with controversy. Lord Fraser of Carmyllie, a prominent Scottish politician, launched a public inquiry into the construction in 2004. His conclusions were that the handling of construction, by everyone from consultants to contractors and members of the Scottish parliament, ought to have been better managed in order to avoid the massive costs and delays. Despite criticisms, the unusual building has attracted critical acclaim for its architecture, and it was awarded the 2005 Stirling Prize for the best building in the UK.

The white elephant, which was planned to handle up to 10 million passengers a year, opened in 2008 but attracted only three low-cost airlines and just several thousand travellers in the first 12 months. In 2012, the airport's owner went bust and all operations ceased. The site was eventually sold in 2015 to a Chinese-led consortium of investors for a measly €10,000 ($12.1k/£8.8k). Three years later it was sold on for €56.2 million ($68.1m/£49.6m) to Ciudad Real International Airport SL and in 2019 even received its first flight, although it had no passengers. However, the pandemic has finally brought it to useful life as a storage facility for planes grounded due to lack of demand.

During the early 2000s economic boom in Spain, the former leader of the Galicia region, Manuel Fraga, set out to build a sprawling complex of six buildings dedicated to showcasing Galician culture. He enlisted the help of American architect Peter Eisenman and set a budget of €129 million for the entire build, the equivalent of $214 million (£156m) today. In 2011 when it was still only half-built, it was reported that the building had already cost more than triple that, at €400 million ($484m/£353m).

Galicia's flagship cultural project now comprises four large empty buildings and two big holes in the ground. In 2013, Spanish newspaper El País estimated that the complex would set Spanish taxpayers back at least another €170 million ($206m/£150m), making it simply unaffordable in a time of austerity. With the upkeep and millions more dollars haemorrhaged on unpopular exhibitions, the Galician government decided to end work and so the project remains incomplete. 

Dubbed “Dubai's ultimate folly” by Guardian journalist Oliver Wainwright, The World was unveiled to much fanfare in May 2003. Work began that same year on the ambitious archipelago of 300 artificial islands off the coast of the Emirate, but came grinding to a halt in 2008, due to the global financial crisis and collapse of the Dubai property market. Investors found themselves seriously out of pocket. 

The owner of Great Britain Island was jailed for fraud, while Ireland's proprietor took his own life. In 2009, reports suggested several islands were sinking into the sea. Lebanon was the only developed island until construction began in 2019 on the $5 billion (£4.1bn) Heart of Europe, a six-island development that was expected to open by the end of 2020. Although work on the project has continued throughout the COVID-19 outbreak, there has been no confirmation of the islands' opening and welcoming visitors just yet. The majority of islands remain untouched and doubts persist over whether the entire megaproject will ever be completed.

First proposed back in 2002, the American Dream Meadowlands Mall in New Jersey (formerly known as the Xanadu project) quickly turned into an American nightmare. Beset by everything from investor bankruptcies and legal challenges to ballooning costs and construction delays, the sprawling retail and entertainment complex was initially slated to cost $1.2 billion (£876m) and open in 2007. The cost is now expected to come in at $5 billion (£3.8bn).

Construction of the East Rutherford mall began in March 2005 but the opening date was pushed back and the mall's parent company ended up going bust in 2007. A slew of badly executed hand-offs, bankruptcies, litigation and countless other issues, including the partial collapse of the roof, have further delayed the megaproject, which finally started to open its doors in October 2019. More than 16 years after construction began and currently trying to operate in the midst of a pandemic, the mall has yet to fully open and much of the project is still a work in progress. 

Why did the Sochi Olympics cost 325% more than budgeted, setting Russian taxpayers back $51 billion (£42.2bn)? In a word: corruption. This was the most expensive – and controversial – Olympics in history due to corruption being endemic in the Russian construction industry. Two members of the opposition party, Leonid Martynyuk and Boris Nemtsov, claimed in a 2013 report that up to $30 billion (£24.8bn) of the budget had gone missing in "kickbacks and embezzlement" to President Putin's close associates. 

Three years before the opening game of the 2014 soccer World Cup in Brazil, the new São Paulo stadium set to host the match hadn't left the drawing board. Fast-forward to 1 June 2014, 11 days before the World Cup's opening match was due to kick off, and the Arena Corinthians was reportedly only able to be filled to three-quarters of its capacity for the final test match, with two temporary seating areas unfinished.

Brazil spent $15 billion (£12.4bn) on the 2014 World Cup in total, including $3 billion (£2.5bn) on new and refurbished stadiums, which was three times the budget. Up to 90% of the money for the stadiums came from the public purse, despite former president Lula da Silva’s promise that all stadiums would be privately financed. Droves of angry people took to the streets in Brazil’s major cities protesting that the billions used to fund the event would have been better spent on the country’s depleted healthcare and education systems. While the stadiums were finished on time, only six of the 35 promised public transportation projects were completed to schedule. 

Construction started in 2013 and several hundred condos were completed and sold before it was discovered that the site, which was used from the 1940s to the 1960s as a covert nuclear testing facility by the US military, showed dangerous levels of contamination. In 2018, the company in charge of the clean-up was alleged to have faked the soil tests that deemed the site toxin-free and documents from the US Environmental Protection Agency later showed that up to 97% of the samples were unreliable or falsified. On 1 January 2021, there were renewed calls for excavation of the site to stop, following a string of dust complaints as radioactive emissions continue to affect communities bordering the area. 

Big Bertha was eventually fixed in December 2015 and boring resumed, but a sinkhole that appeared on the site in January 2016 delayed the megaproject further. The tunnel finally opened to traffic in February 2019, three years and two months behind schedule and $600 million (£490m) over budget. Ten months later the Washington State Department of Transportation won a $57.2 million (£41.6m) jury award after it sued Seattle Tunnel Partners for the cost of repairing Big Bertha and other damages that delayed the project.

Canada's most controversial megaproject, this enormous hydroelectricity venture in Labrador and Newfoundland has been nothing but trouble since construction began in 2013. Billed as an affordable and environmentally-friendly way to meet the energy needs of the two provinces, the megaproject is delayed and has blown the budget by quite a margin. Poor planning and botched engineering, among other issues, have pushed the scheme to CA$13.1 billion ($10.2bn/£7.5bn) – more than twice its original budget – and the discussion as to who is footing the bill is ongoing. 

Initially set for completion in 2017, the megaproject is already over four years behind schedule. Parts are up and running; for example, Nova Scotia Power customers have been paying for clean electricity from the project since 2018, but they only actually received power in December 2020. The supposedly green venture has also been blamed for flooding the area downstream of the Lower Churchill River and contaminating the watercourse with toxic methylmercury. The project was expected to be completed in the summer of 2021, but the coronavirus pandemic has delayed it further. 

Europe's most expensive megaproject, the UK's High Speed 2 network connecting London to Leeds will be built in two phases. The first phase linking London to Birmingham (pictured) is scheduled for completion by 2028-2031, while the second phase connecting the capital city to Manchester and Leeds isn’t scheduled to be ready until 2035-2040. The cost of the new network has gone up and up, with the most recent announcement suggesting that an additional £800 million ($1bn) would be needed to pay for asbestos removal and adding a new hub to London Euston station. 

It isn’t just the ballooning costs that make this railway line controversial, but also its possible impact on the English countryside. The Wildlife Trusts charity said that the infrastructure set to span England would make a “deep cut” across the landscape that could “stop nature’s recovery in its tracks”. The team behind HS2 has admitted the project will leave destruction in its wake, as almost 900 properties, 1,000 businesses and around 60 ancient woodlands will be destroyed during construction. The most recent protest action against the project saw nine activists dig their way into one of the tunnels close to London Euston station and occupy the space for 31 days – one of the longest protests in UK history.

Two of the world’s biggest mining groups, Rio Tinto and BHP, teamed up in 2001 to develop what would be North America’s largest copper mine. Planned for a site 60 miles (97km) east of Phoenix, Arizona, the deposit below the land is ample enough that it could provide a quarter of America’s demand for the metal but getting approval for the megaproject has been no easy ride. The site for the Resolution Copper mine is on sacred ground known as Oak Flat and is occupied by Apache Native Americans, who have strongly objected to the development based on the land's cultural and religious importance.

In 2014, President Obama signed a controversial bill that allowed BHP and Rio Tinto to exchange land it owned nearby for the land above the copper reserve. The bill came with the caveat that an environmental impact statement would be needed before the swap could go ahead, and this was published by the Trump administration in the former president’s final week in office. However, in March 2021, President Biden's administration paused the transfer of the land, stating that more time was needed "to understand concerns raised by the Tribes and the public and the project’s impacts to these important resources”. 

At the same time, the local San Carlos Apache Tribe, along with environmental groups, has a lawsuit pending in Phoenix that aims to prevent the transfer of land. The tribe owned the land before the United States was founded and has lived on it for centuries, which caused disputes as to the land ownership. So far Rio and BHP have spent more than $2 billion (£1.5bn) on the project, but there may be a long way to go before any copper will be mined from the area.

A border between the US and Mexico has existed since 1853, but really became controversial following the election of Donald Trump in 2016. Various administrations had already installed 654 miles (1,052km) of fences and barriers, but Trump promised to build a wall that would reach 1,000 miles (1,609km) in length during his time in office as part of his stringent anti-immigration policy. The former president said the project would cost between $8 billion and $12 billion (£5.8bn-£8.7bn) and insisted that Mexico would be foot the bill. 

The project was not only over budget, but the $15 billion (£10.9bn) eventually spent on construction was financed by funds taken from US counter-drug budgets and military construction funding. Mexico did not contribute a single dollar to the work. By January 2021, the Trump administration had installed 452 miles (727km) of wall, but only 47 miles (75.6km) of that stretch were built from scratch – the rest was the reconstruction of previously existing barriers. President Biden will not be picking up from where the Trump administration left off, having promised not to construct “another foot” of the wall while in office, although he has said he will not deconstruct any part of the existing wall. This pledge will make him the first president since George H. W. Bush not to add to the barrier and will leave this controversial US megaproject incomplete for at least another few years.

In 2017 then-President Donald Trump announced that the $10 billion (£7.2bn) factory that Taiwanese electronics company Foxconn was set to build in Wisconsin would be the new "eighth wonder of the world". However, the megaproject hasn't lived up to those high expectations. Trump (pictured at the site's groundbreaking in 2018 with then-Wisconsin governor Scott Walker [left] and then-Foxconn CEO Terry Gou [right]) boasted that the 20 million-square-foot factory, building cutting-edge, flat-screen displays for TVs and other devices, would revitalise US manufacturing and create 13,000 jobs.

However, in April last year Foxconn confirmed that its investment in the Wisconsin plant has been reduced to just $672 million (£483m), with only 1,454 jobs being created. This was after US taxpayer money had been spent on the site, with the village where the factory is located spending $152 million (£109m) on buying up 132 properties to make space for the project, $7.9 million (£5.7m) to relocate residents, and $200 million (£144m) on improving roads and tax exemptions to local governments offering job training, according to records uncovered by Wisconsin Public Radio.

Current Wisconsin governor Tony Evers was quick to point out that the revised deal will save taxpayers $2.77 billion (£1.99bn). However, Foxconn could still receive $80 million (£57m) in tax credits over the next six years if it hits certain milestones on employment and investment.

While Foxconn hasn't gone as far to pull out of the project completely, the factory will not produce advanced display screens as previously stated. At first Foxconn said the factory would actually work on earlier generation screens, but Foxconn's current chairman Liu Young-way has since revealed that the site produces servers, communications technology products and medical devices, and that it could start to produce electric vehicles. For early critics of the project this turnaround might not be surprising, as at the time many sceptics said that no suppliers of parts for flat-screen displays were located near the Wisconsin factory.

An extension of the existing Keystone Pipeline System has always been a sticky subject for the US and Canada. President Biden revoked the permit for an extension, which has transported oil from Alberta, Canada to Illinois and Texas in the US since 2010, mere hours after his inauguration on 20 January 2021, on the basis of the proposed expansion’s environmental impact. This led the company behind the project, TC Energy Corporation, to pull the plug on the project in June last year, even though around 300 miles of the pipeline have already been constructed.

But the following month, TC Energy filed a lawsuit seeking $15 billion (£10.8bn) in damages from the US government as it claimed the US breached the United States-Mexico-Canada Trade Agreement by revoking the permit. As of this February, the provincial government of Alberta is also seeking $1.3 billion (£960m). 

In 2015, the fourth phase of the Keystone pipeline, which would run from Alberta to Nebraska, was vetoed by President Obama based on its environmental impact. The pipeline would carry crude oil sands from Alberta, which require more processing than oil, and therefore emit more greenhouse gases, and its route through Nebraska would have gone through the Ogallala Aquifer, which is the groundwater source for millions of people living in the Plains states, including indigenous tribes.

However, the project was then granted the go-ahead by Obama's successor Donald Trump in 2019, to the delight of oil companies. Protests against the expansion continued until President Biden stepped in earlier this year. In response, Alberta Premier Jason Kenney said that the move would put people out of work and weaken the US-Canada relationship. It remains to be seen what the impact of its cancellation will be on US-Canada relations, or if the Alberta government will win its claim against the US government, but even though it's not going ahead the pipeline expansion remains controversial.

The Nord Stream 2 megaproject, which will add two additional gas pipelines to the existing 761 miles (1,224km) of Nord Stream pipeline that links western Russia and Germany through the Baltic Sea, has been controversial from the get-go. While some see the additional pipeline as a sustainable way to ensure European energy security, others have been sceptical of the project in light of tensions between Russia and its Western neighbours.

But in May last year, President Joe Biden, who still opposes the project, surprised many and waived the US sanctions on the company building the $11 billion (£7.8bn) pipeline, and the executive who leads the firm behind it, allowing construction to continue. The US Department of State also imposed sanctions on four ships helping build the pipeline – which is 95% complete – but this is unlikely to make much impact on the project's timeline.

Construction of Nord Stream 2 has always been under a cloud of controversy. The leading company, Gazprom, has received a number of fines from Polish watchdog UOKiK. The government agency slapped the company with a fine worth 29 billion złotys ($7.6bn/£5.9bn) in October 2020 for not securing Poland's approval for the project, as well as dishing out hefty penalties to the five companies who are jointly financing the other half of the project. Gazprom has appealed the fine.

Then, in January last year, members of the European Parliament called for the entire project to be scrapped following Russia’s detention of Kremlin critic Alexei Navalny – and tensions have now reached a fever pitch over fears that Russia is planning to invade Ukraine. On 7 February, President Biden claimed that America would halt the pipeline in the event of a Russian invasion, while German Chancellor Olaf Scholz said Germany was "completely united" with the US. Its fate is uncertain, but Nord Stream 2 will likely be controversial right up until its completion.

Prince Mohammed Bin Salman of Saudi Arabia recently unveiled plans for The Line, a 100-mile (170km)-long zero-carbon linear city that will make up part of the kingdom’s new $500 billion (£360bn) business zone. Called NEOM, which stands for “new future”, it's set to span a region across northwest Saudi Arabia, Jordan, and Egypt, and will run entirely on renewable energy when it's complete in 2030. The Line will be a car-free, walkable area, where inhabitants live within five minutes of all essential facilities. A crowning jewel in the “living laboratory” environment that developers are hoping to curate, The Line is one of several cities, ports and enterprise zones that the kingdom hopes will house one million people on its completion.

The blueprint for The Line has been over three years in the making and is set to cost between $100 billion and $200 billion (£72.8bn-£141.6bn). This seemingly idyllic project hasn’t been without its controversies, however. The al-Huwaitat tribe has lived on the proposed building plot for centuries, but some 20,000 members now face eviction to make room for the megaproject. There have also been reports of abduction, imprisonment and harassment of tribe members who have refused to facilitate the project.

The Fehmarnbelt Fixed Link tunnel is poised to be the longest immersed tunnel in the world and will stretch 11.1 miles (18km) between the German island of Fehmarn and the Danish island of Lolland. There is currently a 45-minute ferry service that covers the route, but the tunnel will slash travel times to seven minutes by train and 10 minutes by car. Developers also hope that the tunnel will reduce air travel between the two landmasses. Similar projects to the Fehmarnbelt tunnel, such as the UK-France Channel Tunnel, have been built using a boring machine, but this underwater underpass will be put together using pre-built sections of tunnel.

Not everyone is impressed by the project though, and the tunnel has been subject to 10 separate lawsuits from: environmental associations concerned about noise pollution and risk to the reefs that lie in the vicinity of the build; the city of Fehmarn itself; other travel companies that serve the route such as Scandlines and Rødby ferry line; plus three other municipalities and a farmer. All these legal challenges have been dismissed however, and construction is set to be complete in 2029. 

Now read: Entire towns and cities dominated by one company