Feargus O’Sullivan is doing a series in CityLab right now on the “home designs” that define four European cities: London, Berlin, Amsterdam, and Paris. The first one is on London’s classic “two-up, two-down” design, which refers to a two storey home with a living room and kitchen on the ground floor and two bedrooms on the second. It’s a simple design, but one that has supposedly endured.

O’Sullivan argues that for many, or perhaps most in Britain, this is what a “home” feels like. It’s grade-related and there are two floors. Indeed, only 14% of British people live in an apartment, compared to 57% in Germany (a majority). This percentage is much higher in London, with about 43% of people living in an apartment. But about 25% of the population still lives in some sort of attached house.

Home equals house. And for us North Americans, this is of course relatable. But the Germany example is a reminder that this is not necessarily universal. Attitudes toward housing are cultural. And cultures can and do change. I am seeing that happen right now in Toronto. Some of us are becoming less like the British and more like the Germans.

At the intersection of rue Eugene Sue and rue Simart in Paris is a collection of mid-rise buildings that were constructed during Haussmann's renovation of Paris in the second half of the 19th century. They were intended to house some 10,000 workers.

Here's an aerial image of that intersection from Google Maps:

Some people, namely the folks over at The Funambulist, have compared this area to the Kowloon Walled City in Hong Kong as a result of its extreme population density. But unlike the Walled City, this area of Paris still exists today.

The way these blocks are able to achieve such a high population density is by employing compact internal courtyards. In some cases they would be more accurately referred to as light wells.

Here's a fascinating diagram from The Funambulist showing the approximate areas of each courtyard/light well:

I have become very interested in these sorts of European courtyard buildings. They do have their benefits. For one, they offer respite from the rest of the city. But you can also understand why the modernists were so fixated on access to light and air.

This UN report (2018) on urbanization trends is a fascinating way to understand how our world is growing and changing. So today's post is about some of my takeaways. If you have others, feel free to add them to the comment section below.

But first, some definitions.

The UN report considers 3 ways to measure the size of a city, all of which we have used before on this blog. The first is the "city proper." That is the current administrative boundary of a city. The second is the "urban agglomeration" area, which is a city's contiguous built-up area. And the third is the "metropolitan area," which is the approximate area of economic and social interconnectedness.

Above is what these 3 boundaries might look like for Toronto (which is the example they use in their report). About the only one that isn't debatable is the "city proper" boundary; but it really doesn't capture the full extent of a city. Wherever possible, the UN report relies on the city's urban agglomeration area. They also define a "megacity" as a city of over 10 million people.

The largest city in the world is currently Tokyo. However, from 2018 to 2030 it is expected to decline by almost 900,000 people. Whereas, the city in 2nd position -- Delhi -- is expected to add more than 10 million inhabitants during this same time period. By 2030, these are expected to be the largest cities in the world:

Most current megacities are located in what the UN refers to as the "Global South." And 9 out of the 10 cities projected to become megacities by 2030 are located in developing countries. The one exception is London. Though all regions in the world are becoming more urban, the real population growth is happening in Asia and Africa.

Most cities -- 59% of cities with 500,000 or more people -- are at risk of at least one natural disaster. And 3 megacities -- namely Manila, Osaka, and Tokyo -- are high risk for 3 or more types of natural disaster.

Going through the report's data charts, it's also interesting to note that Toronto is not projected to become a megacity by 2030. However, the Toronto area already represents over 20% of Canada's entire urban population.

In the United States, Chicago's urban agglomeration is projected to continuing growing and does come close to megacity status by 2030. The Miami region is similarly expected to grow and is actually right on top of Toronto in terms of population. But the fastest growing regions are, of course, expected to be the city's that can more easily sprawl (Las Vegas, Phoenix, and so on).

Bogotá, Colombia is already a megacity and is expected to add almost 2 million people by 2030. It currently represents about 26.5% of the country's entire urban population. São Paulo remains one of the top 10 largest cities in the world and is similarly projected to add over 2 million people in the same time period, but to a much larger base.

In Europe, it's London, Paris, and Moscow, with the latter two already in possession of megacity status.

Now quantity isn't everything. Despite not ranking in the top 10 in terms of population, both New York and London are widely considered to be the world's preeminent global cities. At the same time, we do know that the size of a city does create certain socioeconomic benefits. Urban agglomerations create agglomeration economies.

If you'd like to download a copy of the World's Cities in 2018 (United Nations), click here.

Charts/Maps: United Nations