Urban Lifestyle

The Hanging City and urbanization 2.0 – taking cities to the next level

It is an undisputed fact that tall buildings offer the best solution for sustainable, high-density living. Unfortunately, they also pose a significant hurdle when it comes to urban connectivity. Kostas Poulopoulos, the founder of SquareOne Architects in Copenhagen, Denmark, explains his vision of the “Hanging City” in this exclusive URBAN HUB interview. Kostas imagines a second urban plane in the sky that interconnects tall buildings both functionally and socially. These massive, multi-level skyplanes incorporate all of the benefits of skybridges, but add more space and functionality. Seamlessly connected using the new MULTI elevator and even drones, it’s not really that futuristic. Everything is based on current technologies.
Urban Lifestyle
An urban lifestyle for the future –  By first recognizing the impact of our city lifestyles, we can pave the path for sustainable economic development and a brighter, greener future.

Published on 13.12.2018

The key to horizontal connectivity

URBAN HUB: How did you learn of the MULTI elevator and how did it inspire you?

Kostas Poulopoulos: We originally came across MULTI while researching more efficient lift types during a tower proposal for another project. We started looking at a double decker lift until we noticed the all-new MULTI.

When we realized its potential, we decided to contact thyssenkrupp Elevator to develop a concept tailored to the technology’s most important asset: its horizontal movement.

It was love at first sight with MULTI. As a child, I had the idea of using mutually repelling magnets to create hovering cars: I had essentially imagined magnetic levitation. I remembered that idea when I took the first commercial maglev train in Shanghai many years later. But MULTI is even more exciting because it affects not only cities, but buildings. It goes into buildings and can therefore shape architecture from within.


The technology is great in terms of reducing the core size and making vertical transportation much more efficient, but the most value-adding aspect is its extra feature, the horizontal movement. Suddenly we get a completely new type of ‘vehicle’ within buildings – one that can move in two dimensions, maybe later in three dimensions. Who knows? This completely transforms the idea of mobility within buildings.

If one could look a bit further into cities, one realizes that there doesn’t need to be a difference between transportation platforms. You could take a kind of metro  and end up inside a building through mag-lev powered channels. This is a very exciting thought, and MULTI could be the technology most likely to make it happen.

Hanging City
Hanging City

Introducing the Hanging City

URBAN HUB: Can you tell us about your “Hanging City” concept?

Kostas Poulopoulos: The Hanging City consists of multiple, interconnected towers, and the MULTI elevator system would run within and between them. The connections offer much more than skybridges. They are multi-level, mall-sized urban realms. Basically, it is an idea of how one could maximize the potential of building high. Right now, the way that we build tall buildings limits circulation in terms of vertical transportation, speed, and capacity.

There’s another aspect of tall towers: generally, the middle areas have a lower real estate value than the bottom and top. Is there a way to increase the value of the middle, ‘duller’ part of tall buildings? How can mix up the functions and generate more activity, more possibilities and, ultimately, more fun? This would make good financial sense. And I think that financial success is easier when projects create a shared vision of togetherness.

If we connect tall towers, not simply with small bridges, but with entire urban sectors – “hanging cities” so to speak – then we will have the possibility to develop plenty of urban activity there, such as shopping, education, and workplaces.

Kostas Poulopoulos: One aspect is especially attractive for workplaces. Since towers only offer limited footprints, larger tenants are vertically separated across multiple floors. Vertical connectivity is not optimal for organizations, however, as it is more complicated than horizontal circulation. It is much more interesting for a corporate tenant to occupy large continuous floors and to have visual continuity. It is also easier to expand horizontally, rather than vertically.

Of course, these ideas would be a utopian dream without the key aspect of transportation, which makes it all possible. It may be technically challenging, but it is within reach, because it makes financial sense. The critical aspect is how this new Hanging City would be ‘fed’ with people and goods. And that would be through something like MULTI.

We came up with the idea of connecting the traditional ground level of a city with the hanging urban level through a loop of elevators, which you can hardly call elevators anymore, but rather a kind of internal metro system.

Hanging City
“Cities like Hong Kong, New York, and other emerging metropolises are literally just a step away from starting to merge their building stock at a higher level. And this can bring about fascinating changes in urbanity. But only if we tackle the transportation! And this is where MULTI jumps in.”
Kostas Poulopoulos, Founder, SquareOne architects, Copenhagen

The importance of horizontal connectivity

URBAN HUB: Your focus on the horizontal seems to be supported by the trend of so-called “landscrapers” for company headquarters. Would you agree?

Kostas Poulopoulos: Yes. This is a very typical trend, especially in Europe. Vertical solutions can work for companies, but horizontal distribution is favorable in terms of circulation, visibility, and ultimately interaction between staff, which is a huge concern of corporate environments today. Still, we know that cities will end up being much more vertical than they are today.

In fact, the future is already here if one looks at Hong Kong, Shanghai, New York, and London. This trend is not going to go away. We will keep going upwards, some places more than others. The world is growing by about 80 million people every year. The UN estimates a population of 9.8 billion by 2050 with a 68% urbanization rate.

Hanging City

Kostas Poulopoulos: We know that everybody wants to be in the same place. But how can we do that? There’s only one way. We have to go up. Yet the higher we go, the more complex it is to come back down. It almost comes as a natural thought that we need intermediate sectors to create shortcuts and move across the city more efficiently. In my opinion, there is a good chance we will be seeing “hanging cities” quite soon and our intention is that SquareOne will be part of this dialogue.

MULTI Towers

Impact on the ground level?

URBAN HUB: Is there a way to avoid the negative impact of these horizontal connections, which could block the sun at ground level?

Kostas Poulopoulos: This could, of course, happen in some areas, but it’s also an opportunity, knowing that most of the world’s urbanization is happening in arid climates with intense sun. Think of cities like Lagos (Nigeria), Mumbai (India), or Bangkok (Thailand). In such places, we will need to approach urbanization with quite different priorities: Providing shade would actually be a good thing because it would make the climate friendlier.

Look at Dubai for example. Here we have a city where you cannot live outside for most of the year. So any solution that provides a sizeable amount of shade would be advantageous.

Of course, we need to consider whether this is the kind of development that goes into an existing city or whether it could start a new city. Or if we even need a city underneath at all. In a future scenario, we may want to allow nature to exist at the ground level: even forests with wildlife. Perhaps even cultivated land, because we know that we’re taking so much space. This could be a way to give some space back to the planet.

All this is speculative, but it is within the realm of possibility.

Inside the Hanging City

URBAN HUB: Can you tell us your vision for what can exist within the suspended horizontal space of the Hanging City?

Kostas Poulopoulos: We envision a whole urban sector up in the air – what we call the Hanging City – with a big void in the middle for light and communications. And we suspend the elevator in a way that it does not interfere with horizontal circulation on the floor. It also ensures that the system is visible for a “futuristic” feeling, because it is something new and interesting.

Hanging City
Hanging City

Kostas Poulopoulos: It is the visibility of the transportation system that communicates this feeling of “we are in the future!” But technology is not the answer. People are. People need to understand what things can do. And to understand, they need to see. So visibility is a key aspect of our design.

There is no innovation in terms of how we use the floor space and how it is rented, but there is innovation in terms of how quickly you can move from one side to the other, how freely you can jump in and out of an elevator pod, and how “big” buildings can actually become in the end.

Indoor horizontal transportation already exists in the form of moving walks, like in airports, but they have the disadvantage of being on the ground and disrupting lateral circulation. The way we’re looking at implementing MULTI would not disrupt circulation at all, but it does visualize circulation within the space.

Hanging City

Flying connectivity

URBAN HUB: And what would you do outside, on top of this horizontal realm?

Kostas Poulopoulos: We have primarily envisioned this area as a park for people, because that is the most interesting option, but part of that space could also provide limited parking areas for flying drones, such as for the police, deliveries, emergency services, or even taxis. This would create an additional level of connectivity for the building. And it can all work together.

The sequence goes like this: the MULTI elevator gives birth to the possibility of a second urban level, which in turn serves as a platform for other stuff to land on. And I think it’s all very promising.

Next steps

URBAN HUB: And what’s next for you?

Kostas Poulopoulos: Our next investigations revolve around incorporating this idea of horizontal transportation precisely in airports, where there are obvious benefits from quick transportation, along with other typologies of buildings that could benefit from this idea.

Hanging City
Kostas Photo

Kostas Poulopoulos

Founder, SquareOne Architects 

Website: http://sq-1.dk/
Instagram: https://www.instagram.com/squareone_studio

Kostas Poulopoulos founded SquareOne, an architecture studio based in Copenhagen, in 2015. He previously worked with Kengo Kuma Architects, HLA–Henning Larsen Architects (Lead Design Architect) and BIG (Senior Architect). As Lead Designer at HLA, Kostas obtained significant experience in workplace, educational, and mixed-used development projects while responsible for the concept design of Siemens HQ in Munich, Nordea HQ in Copenhagen, the Frankfurt School of Finance and Management, the ZSW Centrum in Stuttgart, and Novo Nordisk HQ.