Research by Callum Hoare
Building a football stadium, we presume, is not easy.
There's a great deal to think about, from capacity to feasibility to aesthetics to cost. It's probably an absolute nightmare.
Which is part of the reason the world's biggest arenas inspire such wonder. There's the sheer size of them, sure, but also our knowledge that they took millions of hours of planning and construction as well.
Understandably, not all plans become reality. The real world gets in the way of our dreams.
Having already cast an eye over some of the stadiums that are going to spring into existence in the months and years ahead , we thought we'd delve into another, more mysterious category: those stadiums that were mooted but remained on the architect's page.
Here, then, are some of the best football stadiums that never came into existence:
READ MORE:Future stadiums in pictures
READ MORE:The 20 biggest stadiums in the world
Liverpool
In 2007, the Reds revealed plans for a new 60,000-seater stadium in Stanley Park, close to their current home of Anfield.
Despite enthusiasm from previous owners Tom Hicks and George Gillett, the plan was scrapped after a meeting between US architects HKS and Liverpool City Council.
Following the end of Hicks and Gilett's reign, the club decided to pursue ambitions elsewhere, with a new £150million project to redevelop Anfield to a 59,000 capacity stadium.
Everton
In 2006, Everton looked to construct a new 50,000-seat stadium project in Kirkby, to replace their current home of Goodison Park.
The Premier League side attempted to create a partnership with supermarket giants Tesco, whose chief executive, Sir Terry Leahy, is known to be both an admirer and occasional advisor to the club.
The proposed £150 million stadium plan, which was Everton's third attempt to relocate, was rejected by the government.
Liverpool AND Everton
A Merseyside consortium put forward this weird 'Siamese stadium' plan back in 2010. The two arenas – one for Liverpool, one for Everton – would have shared a "central spine", which could have brought some savings in construction.
Unsurprisingly, this proved not to be much of a goer.
Portsmouth
Renowned for their design of the Allianz Arena and the Beijing National stadium, Swiss architecture firm Herzog and de Meuron produced plans for a brand new Portsmouth FC stadium to replace the historic fortress of Fratton Park.
The stadium was set to host 36,000 fans when relocated to Portsea, brushing shoulders with the naval bases and Gunwharf Quays' iconic Spinnaker tower.
With a potential financial outlay of £600 million and concerns from local councillors, the club attempted several different designs and locations in an attempt to make these plans work. However the financial crisis of 2008 ended any possibility of a new stadium and the club focused on further developing Fratton Park.
Chelsea
In 2012, Chelsea made an ambitious bid to buy Battersea Power Station and turn it into a new 60,000-seat arena to replace Stamford Bridge.
The plans were certainly very striking, but the Blues did not win the bid , meaning the plans were (power) cut.
Barcelona
The Catalan side have been flip-flopping between redeveloping the Camp Nou and starting a new stadium for yonks now.
This was one idea that was never really likely, but is lovely nonetheless... a 150,000-seat stadium off the bay of the city, linked by a bridge.
Bristol City
In November 2007, Bristol City FC announced a proposal for a stadium to be built on an area of land in Ashton Vale, to replace the Ashton Gate stadium, which has stood since 1887.
Unfortunately for the Robins, after an application by local residents, an independent planner recommended the area be registered as a town green, preventing and future development.
Due to these legal issues, the club decided to cancel the project, which could have seen the Championship side's stadium capacity rise from 30,000 to 42,000.
Tottenham
Before West Ham were confirmed as the new residents of the Olympic Stadium (they'll move in next season), alternative plans were doing the rounds.
Spurs were also keen to take on the arena and even mocked up this image of how matchday may have looked.
Lazio
Fed up of sharing the historic Olimpico with rivals Roma, Lazio were hoping to strike out on their own in the 2000s.
Their proposed Stadio delle Aquile would have had space for 40,000 fans and a transparent roof with solar panels. But the financial crisis put paid to the arena, and new plans for their own stadium now look rather different.
Dinamo Zagreb
A stadium in the shape of a volcano? Sure!
How about a hovering cloud-like white thing suspended above the pitch? Great!
We should all be sad this never happened.
AEK Athens
After being ousted from their historic home, AEK made grand plans to construct a fancy new arena. This would have seated 40,000, but there were objections that held up progress.
Then the financial crisis came along, meaning the plans have been mothballed.
Real Sociedad
La Real hoped to rebuild their Anoeta home in the 2000s, sketching out a plan for a lovely 42,000-seat arena with a retail complex.
But although president Jose Luis Astiazaran hoped it would be completed by 2007, construction never even started.
Estudiantes
The Argentine side planned this amazing arena, with one sheer side and a glass cover for the remaining three sides. But plans have since been scaled back, meaning we'll probably never see this now.
And now take our stadium quiz...