It is not even 20 years since the Emirates Stadium and Wembley Stadium were best in class for stadium design in the UK and around the world.
While both are still considered excellent venues for hosting top-class football and events, there is no hiding the advancements in stadium design in such a short space of time, with the opening of the Tottenham Hotspur Stadium in 2019, and other new stadiums around the world.
But are brand new stadiums the future?
The Old Trafford Regeneration Task Force has initially concluded that a new stadium build for Manchester United would be a more transformative option than redeveloping the existing ground.
It is reported that a new 100,000-seater stadium has been recommended – which would make it the largest in the UK.
Four meetings have taken place around the feasibility of the project, which would see the stadium built on club-owned land adjacent to Old Trafford and elevate the community.
While it is premature to suggest that this is the only direction United will take, it is the favoured route to create a new world-class venue with surrounding benefits.
Last summer, as part of Sky Sports' Future of Football series, with the help of the architects designing and the clubs building the stadiums, we took a look at some of the key developments in stadium design and what could be around the corner in stadiums of the future.
The future of stadium design: The Barcelona model
Renovation and refurbishment is certain to play a huge part in stadium design in the future.
We are already seeing that in Spain. The renovation of one of the world's most famous football stadiums is well underway as the Espai Barca project sees Barcelona upgrade the Camp Nou and renovate 18 acres of the area surrounding the stadium.
Real Madrid are another club going through the same process with the Santiago Bernabeu and in England, Liverpool are continuing to make improvements to Anfield. Those projects come in comparison to Everton, who are building a brand new 52,888-seater stadium at Bramley-Moore Dock.
Jim Heverin, a director at Zaha Adid Architects who has worked on projects including the London Olympics and the recent Qatar World Cup, believes the model adopted by the likes of Barcelona, Real Madrid and Liverpool are the future of stadium design, suggesting Manchester United's Old Trafford could be a candidate for renovation in the future in the same vein as the Camp Nou, particularly with sustainability in mind.
He said: "At Old Trafford, you'd definitely expect them to be thinking about repurposing and not going anywhere else. Look at what Liverpool has been doing with these small modifications and upgrades. That looks like the future and not brand new stadiums.
"I know why Everton moved but that is looking more like the old way of looking at new stadiums, particularly when you have something already that is an asset.
"First, you need to look long and hard at why you cannot upgrade that as the starting point," he added. "There are so many positives to that and for many English clubs in the future that will be their starting point, and it should be.
"You can get everything you need by doing that and also you can save a lot of carbon by doing so."
Multi-functional stadiums a top priority
Another key part of the evolution of stadium design is the ability for an arena to be reconfigured and used for more than one purpose, hosting multiple sports and event types. For example, at the Tottenham Hotspur Stadium it is not uncommon to see football one weekend, American football the following weekend, a music concert in midweek and later this year you'll even see a karting track at the stadium, which will be set up perfectly for each individual event.
Chris Lee, who is the managing director of global design firm Populous, who were the architects and lead designers of the Tottenham Hotspur Stadium, will have seen this change first hand from his involvement with the Emirates Stadium project and then as project director of the Tottenham Hotspur Stadium.
Not only do these events allow a club to increase their revenue and bring a wider programme of events that can be enjoyed by spectators, but it also provides a more sustainable stadium that can be enjoyed for many years by a huge number of people.
For new stadiums all over the world, being multi-functional with, for example, moving pitches and a retractable roof to help facilitate multi-use design, is a top priority.
Lee said: "From a societal perspective, having these big venues sitting in the middle of our communities where they are important but then being able to be used literally seven days a week, whether it is your local football team, rugby, NFL or concerts, I think that is really important from many perspectives.
"From an architect's and designer's perspective, being able to reconfigure space is really exciting. We now have the technology to be able to have huge bits of buildings literally moving to be able to reconfigure them, so they are all perfect.
"We tried this as architects in the 60s. We saw great visionary stadiums like the Aloha in Hawaii where stands moved or roofs moved, never particularly successfully, but now I think we are at a point where we have engineering technology where we can genuinely reconfigure buildings.
"Every stadium and every location is different," he added. "But we have to work with our clubs and our partners to see how we can accommodate the multi-use piece, but accommodate it so it is perfect.
"If you looked at Tottenham, it was designed clearly as the perfect stadium for Spurs. Premier League football was at the heart of it, but it is also really the first bespoke NFL stadium built outside of the continental US.
"Sightlines work, locker rooms work, everything works, and when you go in there for a Tottenham game to an NFL exhibition game, it's a different venue. It feels different, it looks different and works perfectly for both codes."
The importance of community
There was a trend, particularly in America, for stadiums to be pushed to the outskirts of towns and cities. However modern stadiums have moved back into the heart of their communities.
The stadiums are now the centre piece of the local community and are a hub of activity all year round. It can also lead to a regeneration of the area as improvements are made to the local facilities and transport links in the area, benefitting the whole community.
An example is Fulham's new Riverside Stand – designed by Populous – which will not only increase Craven Cottage's capacity by 3,000 seats to 28,000, but will also house restaurants, bars, a hotel, health club, conference and event spaces, and a swimming pool.
The project will also see a riverside walkway open that will help provide community amenities on matchdays and non-matchdays, and also allow the public to walk along the banks of the Thames between Hammersmith and Putney bridges for the first time.
"When we look at our cities, particularly in the UK and around Europe, our cities grew up around these buildings," Lee said. "They are part of our fabric and part of our daily lives. The game on a Saturday or Sunday afternoon, the circus comes into town and the stadium changes.
"I think it is important the stadiums stay in our communities. If we looked in the 70s and 80s, there was a move on an urban planning level to say these buildings are bad neighbours and we'll push them to the edges of the cities.
"In America, cities moving their stadiums to the outskirts and surrounding them by literally acres of black top car parking was the norm and then in the 90s, and actually with a baseball stadium we did in Baltimore at Camdens Yard, it was to help the clubs and the stadium are actually good neighbours and they are good regenerators.
"A key part of the future will be how we can move stadiums sensitively back into our cities, keep them there and then bring the life, the fans and the regeneration that spills out from them into our local communities."
Heverin also believes stadium design should be and will be pushed in the future to come up with new ways to involve the communities.
He said: "We should be pushed to think of more interesting ways to involve the community.
"We have a project where we've looked at a ground concourse that could also work as a market. You can set up stalls in the concourse and really use the space as a covered market out of matchdays.
"It's a really interesting way to look at the concourse, a more public way rather than just for those who pay a certain amount of money, for example to use conference facilities."
The sustainability challenge
Heverin is currently project director for of the Eco Park Stadium project for Forest Green Rovers.
Sustainability is an issue in all walks of like and a topic for everyone to think about, but in particular in architecture and construction it is a critical issue.
The brief at Forest Green Rovers is to create the world's greenest stadium as the club look to raise the profile of sustainability in sport, with Eco Park marketed as "the world's first timber stadium."
Heverin, who believes football needs to help raise awareness of sustainability, is hopeful the project can help show what can be done in the future as the environment continues to be at the forefront of everyone's thoughts.
"The amount of carbon involved in stadium construction is a big subject," he said. "Football needs to be cognizant to that as much as anyone else.
"There's a responsibility there to make sure that everything is heading towards net zero.
"The brief at Forest Green was to make the stadium net zero," he added. "For the owner, the stadium needs to be an embodiment of his sustainability and low carbon principles.
"When you look at a club like Forest Green Rovers, it's interesting how good they are at chasing net zero and their carbon considerations through the whole supply chain.
"It's not just stadiums, where is the kit coming from? Where is the food coming from? What do we use as fertiliser? Where is that coming from? They question everything and are making sure it's sustainable and coming from renewable resources. They are taking responsibility for all of that and if a small club can do it, the bigger clubs need to be doing it too.
"I hope that is the value that comes out of a stadium and project like Forest Green Rovers. It shows that you need to be doing this and it is part of the future of being progressive off the pitch as much as on the pitch."
For Barcelona, sustainability played a part in their decision to upgrade the Camp Nou, along with what the new campus can bring to the surrounding neighbourhoods around the stadium.
Alex Barbany, head of business development of the Espai Barca project told Sky Sports: "In the current times, sustainability is a given. You cannot just go ahead with a project like this without giving thought to sustainability.
"At Camp Nou, we are preserving the first two tiers and building the third from scratch. One hundred per cent of the gravel is being recycled, 50 per cent of it will be recycled into our own project and the other will be used for other projects across the city after we reached an agreement with the town hall.
"We are paying special attention to delivering solar panels on the roof so we can use renewable energy for our own consumption in the building.
"Sustainability has to be the norm all over the world. The fact we are renovating the stadium and not demolishing it and building it as brand new, that makes us feel proud."
Barcelona, who enjoy a huge number of visitors to the club, are equally proud of the part their new facilities will play as they look to make their campus more "relevant in the minds of the residents and the local community" with site that will have a constant stream events all year round.
Barbany said: "There are very few stadiums around the world that sit at the heart of a global capital city like Barcelona, which has a huge touristic graphic and flow.
"There are very few of those and new projects which are being built in such sizeable and central locations of an international appeal like Barcelona.
"If you add on top of that the strength and the quality of the brand of Barca, that sort of sizeable, central location within a city like Barcelona, we believe it makes it truly unique.
"Having the luxury of the central location and the flexibility and land around the stadium is making it possible to do what we are doing. That is what is enabling us to deliver that community element and make the neighbourhood and the city truly become part of it, especially beyond matchday.
"On non-matchdays, roughly 95 per cent of the traffic on campus is from tourists and visitors. One of our main challenges is to become much more relevant in the minds of the residents and the local community so they are just not thinking about us on a matchday but to have rotating content which makes the Camp Nou and the arena relevant, in terms of entertainment options on any given day or weekend.
"You don't always have the opportunity in your lifetime to reshape the largest stadium in the world and to develop a brand new campus in the city centre of a city like Barcelona, which pretty much everyone in the world knows what it is and where it is.
"This will be the true legacy of this club for the next generations, and that is what keeps everyone so excited about the project."
What's next? Innovations and the future
Barcelona are also looking to the future, revealing the Camp Nou upgrades are a "catalyst for the digital transformation of the club", and they are not the only club keeping an eye on the digital and technological revolution.
With the global reach of the world's top clubs continuing to grow every season, increasing profile beyond the physical footprint of fans attending the stadiums will be high on the agenda as virtual and augmented reality is explored
Speaking to Sky Sports, finance expert Kieran Maguire said: "Looking forwards, there is talk about the rise of the metaverse – the ability to use augmented and virtual reality to bring a matchday experience to people's own homes.
"Manchester United claim to have 1.1bn followers around the world. So, instead of Manchester United being limited to 75,000 people being able to attend Old Trafford, why can't we have some form of match taking place at Old Trafford physically and then have it also simultaneously being broadcast in some 3D format to New York, Lagos, Melbourne and Beijing, and you've got 40 or 50,000 fans attending there.
"All of a sudden, those people are willing to pay the equivalent of 30 or 40 bucks to be in a stadium or 10 bucks to to have that matchday experience at home."
We saw a small glimpse of what the future might hold during the Covid-19 pandemic when fans were locked out of stadiums for a period of time, forcing them to watch games at home, linking up with friends and family on Zoom.
So, how does this evolve and what does it mean for stadium design?
Populous managing director Lee said: "The live remote audience is the next frontier for stadium design.
"None of us could possibly predict where digital is going in any sphere, let alone sport, so our job is really to provide an immensely robust backbone that we can accommodate any kinds of potential future digital uses.
"But I think AR, VR and hybrid realities are absolutely going to play a part in our future experience, whether it is in stadium or the remote audience."
"Dallas Cowboys owner Jerry Jones famously said one per cent of Cowboys fans are going to visit the AT&T stadium, so it's how to deal with the other 99 per cent who won't ever visit that stadium but you know are watching that game at the same time in bars and restaurants all around the world.
"It's about how you connect those people and that's the exciting bit," he added.
"We had glimpses of this during the pandemic – the Zoom audiences and the carboard cut-outs in stadiums – but what that showed me was that the live audience is critical. Without the live audience, sport is very different and a very different live experience. But equally, you know that there are 10,000 to 100,000 people and more in little bars around the world, in Sao Paulo, in Sydney and other places, watching that game.
"The question is how we can have those audiences interacting in the same space, digitally.
"Fans, atmosphere and experience, will always play a huge part in stadium design going forward, but digital is probably going to be the biggest change we see."
So, could we be heading to virtual stadiums with family, friends and strangers for matchday experiences in the coming years? Virtual and augmented reality is a topic we looked at in further detail in our Future of Football series.