So, Ricky, in your mind, what is the DNA of cities? Is it literal or can it be a useful metaphor for understanding cities?
Well, the DNA, of course, like the real one in human beings, has many dimensions, and I'm particularly interested in the spatial DNA of the city, and it's a term which I find incredibly useful because it is multi-layered, and we'll talk more about that. But it does allow both the prototype of different cities and the generic species of cities to be, I think, defined in very particular ways, and I think after 25 years of studying cities, there are different typologies of cities, and each one of them has a very particular characteristic. And I think the spatial DNA actually captures these differences completely apart from issues of size, issues of economic development, issues of geography, ecology and everything else.
So I think, to answer your specific question, I think it's a very real thing, but it's also an incredibly useful abstract tool, an analytical tool to help us, who are trying to understand cities and also influence policy, begin to say how might this city respond to this sort of investment change, modification, regeneration, as opposed to not? So it's also trying to get away from the straitjacket of large cities, port cities, beautiful cities, sprawling cities, etc.
And what traits then might cities have? What would you identify as being in the genetic code of a city with this spatial lens?
Well, the spatial DNA of a city is not unlike a sort of CT scan or an MRI, so it's like a CT scan or MRI of a human body. That's how I literally envisage it. In other words, it's not a chemical formula like the human DNA. It's literally a sort of a visual representation of its essence. So if we take this analogy with the human body further, there are the bones, there are the veins, and there's the nerve system. And I think cities can begin to be defined in that way. The main infrastructure of a city is its space, the streets, the alleyways, the connectivity that makes up the whole body and feeds its economic life, its cultural life, its social life, is what I would call absolutely essential ingredient of a spatial DNA.
So I'm focusing on the public space structure of a city, which typically is at the ground floor level, but not only. We know that in some parts of the world, there are cities where people connect through rooftops. There are other parts of cities where people connect below ground because of temperature issues. So where we humans are able to walk, connect, interact is at the heart of this point.
So why I am interested in the DNA, and this is where people like Greg, who studies the politics and the economy, on one side or Richard Sennett and Richard Florida on the other and I are all interested in it, is because this spatial DNA is also the connection to society. And how these two dimensions actually come together is very, very important. So I'd like to transgress the boundaries of the classic planner, the classic social urban sociologist and the classic urban designer. And I think that's where spatial DNA becomes critical in understanding the spatial and social dynamics of cities.
So just to make this even more precise, Ricky, can you just talk about two cities that are in some ways similar but in other ways have very different DNA and what the difference is as you see it?
Let's take Paris and Barcelona. So both of them have a very clear grid imposed onto, in the case of Paris, a pre-existing medieval structure, and in the case of Barcelona, a 19th-century grid grafted outwards onto the existing structure, and you can literally see the DNA of that city in terms of how these two different systems operate, by which I mean the relatively new – the 19th century onwards – and the old.
So what becomes fascinating in the DNA of Barcelona is that the public life of the city is lived out in the major avenues and streets like the Diagonal, but there's a much more intimate scale that happens in the side, in the little interstices between the lateral blocks, let's call it that, with the chamfered corners, but also in the older city.
In the case of Paris, instead, you have two different systems practically operating. They don't intersect in such a, I think, sophisticated way. You have the Paris of Haussmann, which is quite formal. You're either going down one of the big avenues and have the Place de la Concorde and a massive monument on access, or you go to another part of the city, which is in a way more confused – in a good way, I mean that – and have a much more complex relationship between public space and the major infrastructure system. So those could be two examples. But we can come to more if you want.
Very interesting, Ricky, and you said just a moment or two ago that you thought that the different DNA affects the adaptive capacity of cities.
No, that's very, very important. So let's take, then, Manhattan. But what is extraordinary about the city created in 1811 is that someone, in fact, some men, all men, drew the famous plan, which then became the Manhattan grid. How many years have passed since 1811? We're talking about at least two centuries. Hundreds of years have passed since then. What is extraordinary about the Manhattan grid is that buildings have come and gone. Buildings that were two stories high were replaced by 10-story warehouses. Those have either been readapted and turned into cool artists' places, which are now being bought by trillionaires who like to live in the same place. Similarly, in parts of midtown or downtown, the grid remains the same, but the building form has literally – not doubled, quintupled or gone 20 times higher, but always adhering to the principles of the grid itself.
So in that sense, Greg, I would call this spatial resilience at its extreme and its most successful, because in many ways, if you look at over time how Manhattan has changed, of course, all the buildings in one way or other have changed – the occupations, the activities have changed, but the grid remains the same. But interestingly, if you think of this at the building scale rather than the urban scale, exactly the same could be said of the Georgian house, invented as a building for eight members of a family with four members of staff who lived at the bottom, etc. Then middle-class families couldn't afford to live there anymore. Then they become something where each floor is a flat. And then today, they have been bought by Russian millionaires as mansions again. The house has remained exactly the same, just some doors have been added. So I think this notion of the resilience of the built form or the urban grid is part, absolutely, of the DNA.
Ricky, thank you very much. And by the way, this is brilliant and fascinating. What do you make of the city that has more than one vernacular, a city that may have been a Roman city, and then it was a medieval city, and then it's had modern extensions? Are there some cities that have more than one DNA in the way of using that language?
It's introducing more than one DNA. Its DNA is exactly what you said. It's the DNA of Rome, the city that I was lucky to grow up in, is about layering. It's not that there are three DNA's layered on top of each other. And what do I mean by that? You can stand in front of the Pantheon, a building more or less built exactly 2000 years ago. The ground floor of that building is three metres below the rest of the city around it. But the public space in front of it has now got medieval buildings all around. And you turn left, and you come to some of the most extraordinary Renaissance churches. You turn right, and you come to some of the most amazing baroque buildings. And literally in section and in plan, you experience these different histories. So the basements of the Renaissance Baroque buildings have actually got Roman features. And in some cases, they've stolen the capitals of Roman columns from round the corner and put them in the in the upper-level rooms.
So I use that as a caricature of how layering is important. And my comment on layering is that it enriches the spatial experience of a city. Why? For me, the most interesting cities are the ones that have the most complex DNA, the most dumb cities in the world are the ones that have a one-dimensional DNA. And unfortunately, most cities designed in the last 50 years belong to the second and not to the first. So time is very, very significant in enriching this experience.
So the genealogy of the city actually becomes very important, in your view, I think?
Now, what I would say is that you want to avoid being inbred. In other words, it gets more interesting when you have a bit of influence from North Africa affecting Spanish cities that then marry with Catholic principles of top-down planning. And so it goes on. Then it becomes rich and complex.
Are you saying, Ricky, that a city with more multiple layers of DNA gets more benefits from that DNA? And if so, what are they?
Well, this is where a question you're going to ask me later, I'm going to answer now, which is: having a special DNA of type A, B or C doesn't in any way automatically mean that the life that is inhabited on that structure is the same, because this is where urban culture, made up of people like us, applies completely different models of sociability and complex urban existence.
So, for example, if you have a society where women are not allowed to use public space or children are not welcome, and/or people of different ethnicities or diverse income groups, the same spatial DNA becomes completely different in terms of how that organisation is lived. London in the late 19th century, when it was bursting or becoming the big major megalopolis, suffered, according to those running the city from having too many dark alleyways, the famous rookeries where the underclass of the city, the working class, were able to scurry away when the police came to try and track them down.
As a result, quite a few of these areas were knocked down and then rebuilt, like Arnold Circus in east London, with housing effectively to control the lower classes so that the emerging classes could live in peace and quiet. These so-called rookeries, if we were in Luqa or we were in the back streets of Prague, we would say these are exactly the beautiful little alleyways which make up the complexity of life, and you can take photographs of all that. So in other words, how these spaces are inhabited depends on a whole series of complex social infrastructures, which will be totally different in a 19th century with a large proletariat as opposed to, today, Stockholm or Copenhagen with a relatively flat society, greater equity between the different groups who live there. So, again, I don't want to, at all, make a very naive one to one correlation between space and social cohesion. It's never that simple.
Is there anything that you think is important for us to understand about how cities acquire their DNA and who or what is responsible for the different shapes that cities take in the way that you understand it?
Well, at the heart of your question is basically the question about informal natural process of agglomeration versus top-down planning. this is something which is just as important today as it was then. as a student of London, I'm endlessly fascinated. And in fact, London was never planned. And the only two attempts to replan it after the great fire of London were thrown out of the window in months. It was rebuilt exactly as it was. And probably the only form of planning that has worked, and it's brilliant, is the 1943 greenbelt decision to stop the city from growing.
So going back to your question – in a way, not only what is it, but who decides what are the ingredients – I think there is no one answer to that question, in the sense that some cities literally grow organically and some megacities have grown and continue to grow to a degree organically. And when you ask this question today in the face of 21st-century rapid urbanisation, we also don't have to remind ourselves that between 40 and 60 percent of African and Asian cities are totally informal and totally unplanned.
Now, that doesn't mean they don't have a DNA. They have a DNA. When you go to Dharavi, when you go to Khayelitsha, there's a very recognisable pattern of streets and alleyways and public spaces. Some of them are used in regressive ways, and others become the lifeblood of communities which find it very difficult to get by. But of course, then there is planning. And planning is either about controlling informal processes to provide a city with the essential ingredients, by which I mean water, sanitation, light, gas access and access to jobs, access to public services, etc., which sometimes have to be grafted onto an existing infrastructure. I would say actually that's the majority of cases.
So the city of Rome, that I was, again, brought up in, yes, it has an ancient Roman plan of the cardo and the decumano, but it very soon becomes rather confused by the Middle Ages and then the Renaissance. But the 20th century had to then introduce railway stations. It had to introduce all the great institutions, the hospitals and the libraries and other things. And it's going back to Greg's question about time, how these different layers are juxtaposed both in plan and section is part of the resilience of the DNA to deal with this.
So going back to whose is it, or who is it, it's not that simple an answer. And thank God for that, because these top-down cities where there's one vision – whether it's even a mayor or a president or a civic leader, not to mention a company, which says "this is how it's going to be and this is how it's going to remain forever" – always fail. There's hardly any utopian city that was created from the 16th century on which is actually lived as envisaged. No. And some pieces of a city that we know very well – Canary Wharf – were sort of thought up that way. But, boy, did they have to quickly start saying, "Oh, let's have some housing here. Oh, we need public transport." And it's going to take another 20 years for it to feel like a normal piece of London. But it's interesting to have that example right under our nose in terms of understanding that.
I think one of the aspects that we haven't talked about in terms of the DNA, and I've insisted on describing the spatial structure, is where are the city's different uses and functions displayed or placed on them? And I think in the 21st century, through the arguments of sustainability, we're rightly beginning to see the enormous benefits of co-presence of different uses, one on top of each other and close to each other. We don't, in the west anyway, or global north, have the problems of severely polluting industries that kill people because of the emissions. And therefore that becomes a much stronger possibility. Again, it's all to do with the complexity of different activities above each other.
Then the question is who decides? It's the political infrastructure. And therefore democracy has to be equally embedded into a well-connected spatial DNA in order for it to work, and the two should never be disconnected, and this is where I think people like Greg, people like myself, the work done at Brookings, the work done at LSE, the work done elsewhere, is about putting these things together again and not just talking about cities as a system of governance, independent of the spatial structure.
And do you think that cities understand their DNA? And if they do understand it, how might they use it?
The implication behind your question is that the DNA is like, you know, a document that says, "here's the DNA". And it's not that. First of all, I think you need –and this is why research centres and universities are very important – you need the tools and the methodologies to begin to describe what constitutes the structure of the DNA.
Let me, for example, just give you one visual example, even though we're on a podcast, and then go back to parts of your question. There was a fantastic plan of the city of Rome drawn in the late 18th century by a man called Giambattista Nolli, and he tried to capture – it was one of the first plans ever drawn of this extraordinary place, Rome. And imagine Rome at the end of the 18th century with some of the most extraordinary buildings in terms of St. Peter's, Michelangelo domes, everything, all there. And he drew it in such a way that all the buildings, independent of use, were in black, and all the spaces that you could walk through day or night or in white. So the courtyard of a cloister that you could walk through would be drawn in white, the little alleyway to deliver bread in between the great Palazzi would be also drawn in white, etc. This diagram is the best representation I can think of of the DNA.
One of the very interesting 20th Century urbanists based at Cornell University used this methodology of representation on – let's call it "the worst" modernist examples, whether it's the Brazilia-type city or the plans of Le Corbusier to rebuild the centre of Paris. This is the architectural critic called Colin Rowe, who won the RIBA gold medal a number of years ago and has since died. And if you do a drawing of the modernist city, instead of having a wonderfully messy, structural black with all these veins going through it, you get just a big block of black surrounded by a large amount of unusable and unpleasant oversized public space. And of course, the impact of the motor car on the experience of what these spaces are like is very dramatic.
So the representation of what constitutes DNA is part of the process that you're asking me about. How do you describe it? How do you see it? Just like you ask, today, a brain surgeon, "How do you use contemporary techniques for visualisation based on laser technologies and most advanced technologies of that sort?" – in cities, we have to continue updating the way we look at cities. Some of the work done at MIT, I think, is very interesting from this point of view, and elsewhere.
The question of how it's used, to go back, is a political question. And it depends on whose voice is represented, which is nearly independent of the DNA. Democracy means that a smaller number of people have a voice and don't only have a voice about their immediate neighbourhood but have a say in the bigger picture. So in the London case, you have a mayor who gets elected, who then drops a London plan. If you don't like what he does, you kick him out after four years. If not, you have to go with it. Barcelona's similar, and there we go on. Interestingly. American mayors do not have the capacity to control future development, let's say, recognising and building on the DNA. European mayors, and I'm sure elsewhere, they do.
At a very basic level, Ricky, does understanding the DNA, or being able to visualise it in the way you described, enable you to decide or at least to understand what is appropriate and what is not appropriate in terms of the use of space? Or does it help you to understand what will work with the vernacular or work against it? Does it have practical implications like that?
Yeah. So let's take a real-life example: the City of London. So this is a place that for at least a thousand years has been the centre of business globalisation before the term was invented. And a pretty aggressive pro-development, pro-market approach. What is fascinating about the city, having spent many weeks now filming it again, is that in the end, that spatial structure that I was describing in the Rome plan is still there after 7-800 years, but you have Lloyds of London there in front of it, you have the Cheese Grater. Today, you have 22 Bishopsgate, the tallest building in the city.
It's very clear what you shouldn't do when you understand the DNA of the City of London. It's made up of a series of networks and connections, and you should not break those up. And the planning regime, which I actually have been very supportive of there, has recognised that. Said, "OK, we can have a 21st century skyscraper, but along Bishopsgate." Bishopsgate has been there since Roman times, you've got to still have that, you can't occupy and gobble it up. You turn the corner on Leadenhall Street, and you have to have buildings addressing the street frontage. So by reading the DNA, you can actually go with the flow in in the best sense of the word. So I think it's a fundamental planning tool that hardly any city uses.
So, Greg, we have a lot of education to do with our city leaders. The reason behind that is, unfortunately, sometimes this discussion is seen as very aesthetic, you know, it's a bunch of architects just talking to each other about froufrou drawings. Actually, I think it's at the heart of the debate of how a city actually works and competes.
Another person we're going to interview in this podcast is going to talk about the acupuncture, the feng shui, the flows of the city, the homoeopathy of the city. And, of course, those are other metaphors that describe the things you're talking about.
So, Ricky, does the concept of the DNA of cities leave anything out about the way cities evolve or how we might understand cities' evolution?
Well, I think I've already addressed this, because when I talk about the spatial DNA, I'm talking about a physical infrastructure which can be completely used or abused by different social and political systems. So what it leaves out, but that's a strength, not a weakness, is who inhabits it and how. And I think in that sense, to try and match the two becomes part of our role as good urban leaders. How do the two connect or not?
The worst-case example was the one I gave of London at the turn of the century, where an environment begins to perform in such a way that it provides a threat to the establishment, that they just tear it down, and we have seen that happen. And there's an attempt to change society by demolishing neighbourhoods. This is completely, unfortunately, an experience we not only have seen, but are seeing today as we speak, being implemented in different parts of the world, whether it's in parts of Ethiopia where we've been working recently or frankly, elsewhere.
In the end, Baron Haussmann did make quite a substantial change to what was there before. Therefore, what is left out of the spatial DNA discussion is the politics and the social habitation of it. But it offers, and very importantly, a mechanism by which you can begin to describe this so that you don't end up, which is something I feel passionate about, with a description that this sort of city is good and that sort of city is bad. There's no such thing as a bad city. There are cities that do things better than others, and there are cities that actually become dysfunctional over time with different political systems.
But I think this is where resilience really does come in. I wanted to avoid using the sprawling city is as opposed to the compact city. But where does that take us? There are 50 types of sprawling city. And you could redefine parts of the whole of Holland as a sprawling city with multicentre. It's a bloody good system, if you think of it that way, and the interconnections and the possibilities of actually supporting all these different centres in different ways.
So questions of scale come into it, which are over and above, in a way, the DNA or need to be included in the discussion. But ultimately, the political structures that support or enhance the sociability of the DNA are a powerful piece of work that needs to be understood to give a 360 understanding of cities.