How Cities have been Shaped by Defense

So in your spare time you’re looking at an aerial view of London on your favorite online mapping service (as one does), when you notice a street called London Wall.

London 2

And as you’re looking at your map, you notice other wall-y things, like Old Bailey and Houndsditch.London 3And then you notice that perpendicular to these wall-y things are lots of gate-y things: Ludgate Hill, Newgate, Moorgate, Bishopsgate, Aldgate.

London 4And at about this point you start to see a shape and realize,London 5You can learn a lot about a city’s history by looking at a map of it. If you know what to look for, you can see how high places, walls, and other fortifications had a major effect in shaping our cities.

Early settlements all around the world were formed on the tops of hills. Hills are naturally defensible, because they allow you to see a greater distance and force your enemy to expend energy getting up the hill. Even in the large, flat expanses of the Levant, cities would create the advantages found on the more natural hill forts of Europe by building giant piles of dirt, or tells.

Tell Barri in Syria. From

It wasn’t a stretch to get from “let’s build our city on this hill” to “this hill would be really great with a wall around it.” And thus, the citadel was born.

Citadel of Arbil in Iraq. From

The citadel, of course, had different regional names, including the acropolis and the oppidum. Initially they were built of whatever was available, be it stone, wood, mud brick, or rammed earth. But in most places, stone or masonry eventually prevailed.

Groß Raden Archaeological Open Air Museum in Germany. From

In many cities, the fortified citadel grew to house only the city’s political and/or religious elite, while the normal residents were outside of the walls and subject to attack. But eventually the rulers decided that it was worthwhile to defend their soldiers, scholars and artisans, and cities began erecting full perimeter walls.

The weapons these walls were built to defend from were mostly just guys with swords, arrows, and in some cases fairly light siege equipment. As such, they didn’t need to be particularly thick, but they did need to be high. These walls often followed contours and were somewhat organic. They had fairly regularly spaced towers from which to shoot arrows or throw rocks, and were usually the joints at which straight walls would change direction.

The walls and towers of Rothenburg ob der Tauber, Germany. From

More importantly for urban design, the city wall provided a natural growth boundary. Especially during the uncertain times of the European Dark Ages and the invasions of the Germans, Huns, Slavs, Vikings, Arabs and Mongols (that’s everyone who invaded anything between the end of the Roman Empire and the introduction of the cannon, right? You get my point), there was a huge incentive to be inside the city walls rather than unprotected in the fields or the lawless countryside. The European feudal system only added fuel to the urban fire; peasants and slaves alike would flee to cities to escape their masters. In Germany, the law was that a serf was a free citizen of a city after a year and a day, thus the phrase Stadtluft macht frei nach Jahr und Tag (“city air makes you free after a year and a day”), better known for its shorthand, Stadtluft macht frei (“city air makes you free”).

The end of this phase of wall building came with the cannon. Unlike previous siege engines like the catapult and trebuchet, which threw objects over city walls to cause damage within, the cannon, with just a few direct hits, could pierce a wall, allowing for foot soldiers to enter the city. The vertical wall laid out perpendicular to the enemy allowed the cannon ball to focus all of its energy on one point, causing maximum destruction. The solution was to not try to necessarily stop the ball, but to diminish its destructive power by deflecting it. And thus the star-shaped wall was born.

These walls were not vertical and not perpendicular, but formed a jagged, pointed wall that sloped back toward the city. The angled and sloped walls, which were also much thicker, made it more likely that a cannon ball would simply bounce off and roll away harmlessly. The star points on the walls also allowed soldiers a forward position from which to attack the enemy, with the civilian population located further back from the action.

Naarden, the Netherlands. From

Star-shaped walls were massive feats of engineering, and only the wealthiest cities could fully enclose themselves within them. Some cities would create small forward military towns which would be heavily fortified, such as Palmanova outside of Venice. But in many cities would simply build a star-walled fort at a strategic location, such as the confluence of two rivers (Fort Pitt at Pittsburgh) or on the harbor (Fort McHenry at Baltimore).

Fort McHenry guarding Baltimore Harbor. From

There aren’t many cities whose star-shapped walls or forts remain. That is because they take up a huge amount of land, and as many cities, particularly in the west, began to feel less threatened by foreign armies, they wanted to use that land for other purposes. Many of these areas were redeveloped for public use. For instance, the former site of Fort Pitt in Pittsburgh is now Point State Park, where only traces of the former fort (as well as its French predecessor, Fort Duquesne) remain.

The outlines of Fort Duquesne (smaller, left) and Fort Pitt (larger, right) at Point State Park, Pittsburgh. From Google Earth.

The outlines of Fort Duquesne (smaller, left) and Fort Pitt (larger, right) at Point State Park, Pittsburgh. From Google Earth.

One famous example of a star-walled ring being replaced is the Ringstraße in Vienna. In the 1800s, Vienna had a star wall around its old quarter, but new districts had sprung up on the outside of the wall, and completely encircled it. Vienna was essentially the hole in a fortified doughnut. In the 1860s, the city chose to tear down its old fortifications, replacing them with a ring road, public parks, and major public buildings.

Ringstraße, before and after the redevelopment of the fortifications. From

It was about this time that explosive artillery shells were introduced, which star-shaped fortifications did not perform well against. These weapons also lead to the end of urban fortifications. The radius of damage from explosive shells was just too large for cities to feel comfortable going against, and the defense of cities fell to rings or lines of polygonal forts set back about eight miles from the city. Yet even without the enclosing walls, there was still an incentive to be in the city, where you were protected by the ring of forts, rather than in suburbs of the open countryside. That incentive came later, with the introduction of aerial bombardment and, later, nuclear weapons.

The nuclear era was the first time that the incentive for defense actually pushed people out of cities. When you have a single weapon that can kill hundreds of thousands in an instant and level an entire city, urban areas start to look less like refuges and more like targets. While there were many factors that led to suburbanization in America, the fear of a Soviet nuclear attack cannot be overlooked. One of the many reasons the interstate highway system was built was so that cities could be evacuated in case of an emergency, and one could imagine that those who fled for the suburbs were simply planning ahead.

That being said, there have been several proposals and even a few attempts at creating urban defenses in the nuclear age. There were many proposals for domed cities a la Buckminster Fuller, although his domes were largely meant as a means to prevent air pollution and provide city-wide climate control. The Underground City of Beijing, built during a spat with the Soviets in the 70s, was a network of underground tunnels, featuring shops, warehouses, and even mushroom farms (since mushrooms can grow without light), and supposedly could have held all of Beijing’s population of 6 million at the time. Switzerland, which is just chock full of air raid shelters, intended a double use for the Sonnenberg Tunnel outside of Lucerne, which would have been able to house 20,000 people in the event of a nuclear attack.

Buckminster Fuller’s Midtown Manhattan Dome. From

I think part of the reason that my generation is returning to the city, although it may not be a conscious factor, is that the Cold War is over, and there really isn’t a world power out there with the air force and nuclear capabilities to attack us the way the Soviets could have. While it may have been a perfectly reasonable fear of nuclear annihilation that encouraged our parents or grandparents to leave cities, we don’t have that same fear. The greatest outside threat to our safety is no longer a State with official armed forces, but the small, loosely organized groups and individuals that today are the perpetrators of terrorism. But with few exceptions, terrorists cannot attack a large area at once, and although cities do employ counterterrorism measures, the targets of terrorism aren’t cities, they are usually individual properties or persons. That is why today we are seeing a resurgence of defensive construction, not on the city scale, but on the scale of the individual building.

Bollards, bollards everywhere at HHS in Washington, DC. From

Bollards, bollards everywhere at HHS in Washington, DC. From

While defense no longer encourages us to move to cities as it once did, it allows us to, more than it may have our parents or grandparents. The technology of war, as well as its general presence, may continue to be a factor in how we design our cities in the future, but the city of today is a safe place, and getting safer. As Stephen Pinker points out in The Better Angels of our Nature, violence in the world is on the decline, both on the scales of the individual and the nation state. With less to fear, we may be more able to enjoy the benefits that the city has to offer us.

Los Angeles Isn’t London, and Other Things that are Wrong with California

Recently I was browsing Imgur and came across a set of images depicting the current drought conditions in California.

Lake Oroville, July 2011. From

Lake Oroville in 2014. From

When I looked through the comments, I saw a few gems:

“See this?…See this? This is why I think lawns should be illegal in drought areas. You want a lawn? Move to East…”

“Hey let’s build golf courses in the desert!”

“A**holes need to realize that lush green lawns work in the SE, not SW. Sauce: I’m a f***ing city planner.”

Which reminded me of something that bothers me about California: that 38 million people live in an area that can probably sustainably support something more like one million, and lawns are just one example of cultural artifacts that have made it to California that were based on an entirely different climate. Let me explain:Isnt-01Well, yes, but so what? Well, some cultural features, including the lawn and the detached home, are cultural aspects that arose in England, partially because of its climate, and got appropriated to California in such a way that the environment had to be altered to support it.

The lawn became popular among the English nobility in the late Middle Ages. It arose there because England’s wet weather and moderate temperatures made it ideal for keeping grass green without the need to water, and because before the invention of the mower in 1830 one needed an army of peasants to trim the lawn with scythes. The lawn quickly dispersed to Ireland, France, and the Low Countries, other places with a suitable climate.

When the lawn hopped the pond with the earliest English colonizers of the Americas, it fared decently in the Northeast, which despite having a humid continental climate rather than England’s oceanic, still had sufficient rain and temperatures, although the winters were usually cold enough for the grass to go dormant. Some New England towns had lawns that were commonly owned and maintained, leading to the New England Common. But at this point the lawn could barely even survive in the American South, where higher temperatures made it too warm to keep the grass from turning brown.

The lawnmower was what made the lawn accessible to the land-owning middle class. They became more common with the implementation of the 40-hour work week, and lawn care was promoted as a form of relaxation during the Depression. It was only through irrigation that the lawn was able to leave the Northeast, and even then, only due to massive inputs of fertilizer that it was able to take root in the arid soils of the American Southwest.

Let’s take a closer look at climate. Here is a map of the oceanic climate, where the lawn originated:


These climates are most present in northern Europe, southern Chile and Argentina, southeast Australia, and New Zealand. It is truly barely present in North America, only making an appearance on the wet coasts of the Pacific Northwest around Seattle and Vancouver. Notably, it is not present in California. Let’s look at California’s climate map:


The most densely inhabited parts of California are mostly within the semi-arid (BSh, BSk), desert (BWh, BWk), and Mediterranean (Csa, Csb) climate zones. Where in the world can we find those?



The Mediterranean climate, unsurprisingly, covers much of the Mediterranean, and as far east as Iran. Desert climates, largely uninhabited, cover much of northern Africa, the Middle East, central Asia, and Australia. Semi-arid climates generally ring the desert areas. So maybe a Mediterranean or Middle-Eastern home might be a better model for California. How would that compare to the English-based model of today?Houses-01

Traditional Mediterranean and Arab cultures both used courtyard houses. Exterior walls in these cultures were often plain or even drab, with much more of the focus being on the interior courtyard. By having a smaller landscaped area and using native plants rather than ones introduced from a wetter climate, a household could cut its water use dramatically. The courtyard house also takes advantage of microclimates, shared walls, shading, and the solar chimney effect to naturally ventilate the house and use less energy than the detached home.

An Arab-influenced courtyard in Spain. From

There are many issues facing California: over-development in both the housing and agriculture industries; over-reliance on cars for transportation; and despite their issues, an ever-increasing demand from new residents for housing and services. But one way they can begin to address issues related to water use and sustainability is to adopt a climatically appropriate housing model. Los Angeles isn’t London, so why should it build houses and lawns as if it was?

Floating Village Planned for London


As a follow-up to my last post, I recently found this story about London’s plans to develop an underutilized part of the Docklands as a floating village, along with other new development. London’s housing prices are some of the highest in the world, and with that much demand and that little space, you need to come up with some creative solutions. I’m interested to see how this development goes and look forward to watching it grow.

This City Was Made for Sharing – Shared Space in Urban Design | Knowledge

Exhibition Road in London

Exhibition Road in London. From

In this post, Romy Rawlings makes a great point about how we share our public space–namely, that we don’t like to. The solution to this for a long time has been separated travel modes–pedestrians on sidewalks, bikers on bike lanes or trails, and cars on the “main” part of the road, as well as parking lanes. Recently, however, transportation agencies, particularly in Europe, have been moving away from this model, and forcing different transportation modes to play nice on narrow, single-grade, often alternatively paved and sign- and safety equipment-free streets. A great example is the aptly named Exhibition Road. Rawlings covers some of the successes of the street, as well as some of its failures and challenges (for instance, a special interest group for the blind was opposed to the shared roadway). It’s a good, brief analysis of the effectiveness of these sort of projects.

Home is where the work is: the case for an urban design revolution

A potential layout for a “workhome.” From

Pretty much every day, I commute two hours to work, work in a regular office, have lunch at a coffee shop, and commute two hours home. But today was a special day. I had a meeting closer to home in the morning, then made a site visit for a project in town, and spent the rest of the day working from home on a project I had available on my home computer. It’s nice to work from your couch, listening to music sans headphones, and being home when my wife gets back from her office.

The truth is, a lot more people are working this way than ever before. This post from The Conversation discusses the continued growth of working from home. Despite the growth in telecommuting, and the long history of people living and working in the same place, buildings today aren’t built with this sort of use in mind. Because of this, the London-based Workhome Project has conducted research and design into how to create a modern “workhome.” There are a variety of factors that determine what kind of workhome would be best for a certain situation: work/home balance; degrees of separation between functions; and how many people will use the workspace. They even have SketchUp models of some of the designs for you to get a better idea of how they look and feel. It’s a great resource for anyone thinking of creating a space for themselves or a few others to work at or near home.

Where are you from?

This is one of the first things someone asks when you meet new people, and for me, it’s always been sort of hard to answer. For instance, if I’m traveling, I’ll usually say Philadelphia, since that’s where I live, but it’s not where I grew up and I don’t identify strongly with the city. Usually I either tell people I’m from Pittsburgh, where my parents currently live and where I graduated from high school, or that I grew up in Pittsburgh and western Massachusetts, since I spent six years of my childhood in each place. I usually gloss over the fact that I have also lived in California, Utah, Idaho, and Oregon, because I didn’t live in those places as long and they didn’t have as much of an impact on me, but they are still part of the equation.

But what if I go further back, and think more broadly? I was born in the Bay Area, so sometimes I say I’m a native Californian (this is mostly when I’m comparing myself to my wife, who lived her whole life in California except for her first two weeks, when her family lived in Spokane, so she isn’t a native Californian, like I am). My parents grew up California and Nevada, and their parents in California, Washington, Nevada, and Utah, so I could say I’m from the West or the West Coast. But how did my family get to the West Coast?

This, combined with an on-again-off-again interest in genealogy, led me to map the last ten generations of my family.

Click to enlarge.

My family came to America in two large groups, what I could call Mormon and pre-Mormon. My Mormon ancestors converted to the church in their home countries of England, Denmark, and Norway, and then emigrated to Utah, some of them later spilling out into California. The pre-Mormons came from England, Ireland, Scotland, Wales, Denmark, and Germany, and settled up and down to east coast of the US and Canada, some of them later converting to Mormonism and heading to Utah, with others coming west for new employment, such as mining and ship building.

So that’s the larger, geographic explanation of where I’m from: mostly Scandinavia and the British Isles, where my ancestors came from seeking economic opportunity and religious freedom, eventually settling in the western United States, where I was born and from whence I returned to the East Coast. But geography isn’t the only part of where a person is from; geographically, I’ve lived all over the US, but I consider myself a Pittsburgher because I love the Steelers and Polish food, and a New Englander because of my left leaning politics and the fact that my family has, in the past, made our own maple syrup. So what were the places where my ancestors lived like? I decided to leave out the places where my ancestors moved to or from (the lines on the above map), and focus on the places where they lived for at least one generation (the circles).

Click to enlarge.

Originally I thought that I would spotlight each of the places, but excluding counties there are 32 of them, and that would get tedious, so I’m going to include an image gallery so you can get an idea of what they look like and identify some trends.

Most of the places my ancestors lived in were small towns, villages and hamlets. Only four (Copenhagen, Glasgow, Baltimore and London) are metropolitan centers, and I would only add Walsall and New Haven to to that to make a list of cities. The rest are too small. This makes sense, considering that it is only fairly recently that our world has had more than half of its people living in cities.

Along with being small, most of the places my ancestors lived were very rural. The graph above divides the places based on my matrix of settlement types, showing that they are mostly rural villages. What I think is interesting though is that there are very few suburban places; only Ballerup and Middletown fit this description. Ballerup is a historical town that has been sucked into Copenhagen’s sphere of influence, and Middletown is on the edge of the New York metropolitan area. I wonder how different they might have been when my ancestors lived there. It’s important to note that the suburb as we experience it today, with separated uses, cul-de-sacs, car dependency, and dependency on a larger nearby city, is very much a modern phenomenon, something our ancestors were unfamiliar with. Note: while some might call Walsall a suburb of Birmingham, it features mixed uses and a connected street grid, which give it a more urban character; I would call it a city that is part of the Birmingham metropolis.

I really enjoyed learning more about my ancestors and the places they lived. Check out the gallery below to see more of what these places look like.

Olympic Park Gardens are a Natural for Gold : TreeHugger

A meadow planted in the Olympic Park. From

We’ve talked about the built legacy of the 2012 London Olympics, but there is a natural one as well, as covered in this post by Bonnie Alter. A series of gardens in the park were planted, in true English Garden style, as they would appear in nature. Four gardens depict plants from different parts of the world: Europe, Asia, North America and the Southern Hemisphere. Other gardens were designed as meadows by professors form Sheffield University, including the blue and gold meadows around the stadium known as the “Olympic Gold Meadows.” Some remnants from the areas industrial past are mixed in and create an interesting contrast, while new public art installations are also part of the gardens. It seems like a beautiful park which will be a real asset to the city of London for years to come.

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