Seun Sangga is Seoul's first mixed-use complex.

Constructed between 1967 and 1972, the elaborate structure sits atop a strip of land measuring 50 m x 1.2 km, which had been flatted during the Second World War as a way to contain the spread of fire in the event of an air raid and to act as an evacuation corridor.

It's a modernist development that is very much of this period. It's massive, complicated in section and, in many ways, completely disconnected from its surrounding urban context. Flanking the various buildings are elevated and covered walkways.

So it is perhaps not surprising that this development has followed a similar fate to many others of this era. While it was initially viewed as being quite modern and desirable -- it was one of the first buildings in Seoul to have elevators -- Seun Sangga was quick to start showing signs of decline.

In fact, by as early as the 1970s, the complex became known for its porn shops and a bunch of other informal economy-type activities.

It's an interesting, though familiar, story.

If you'd like to learn more, I recommend you check out this episode of the Urbanist and this article from The Architectural Review. The photos in the article are good accompaniment to the audio-only Urbanist episode, so make sure you flip through them.

I'm so predictable. This is the kind of house that tends to grab my attention: modern design, relatively small footprint (~7.8m x 12.3m), narrow street (~4m), and panoramic views (of Seoul). But what does it take to actually build a house like this in an urban fabric as dense as Seoul's?

If you read TIUM Architect's description (using Google Translate for those of us who don't speak Korean), you'll see that the house was built out of concrete and steel, but that concrete trucks couldn't stage on the narrow and dead-end street.

So what they ended up having to do was build a 100-meter concrete conveying pipe (~328 feet) and staging somewhere else. It was such a pain in the ass that they only wanted to do this for the foundations. The rest of the house was built out of steel. (I think because of the clear spans that they wanted.)

Sometimes small infill projects aren't as simple as they may seem. In this case, the lot size is 92 m2. The building footprint is 51.53 m2 (56% lot coverage). And the total floor area is 136.52 m2.

Photo: Lee Hanul via ArchDaily

As a follow-up to yesterday's post about infill housing and overall urban densities, let's look at some basic math.

The City of Toronto has an estimated population of 3,025,647 (as of June 2023) and a land area of 630 square meters. That means that its average population density is about 4,803 people per km2. Obviously this number will be higher in some locations, and lower in others. But overall, this is the average.

Now let's consider how many people we could actually fit within the existing boundaries of the city (city proper not the metro area) if we were to simply match the average population densities of some other global cities around the world.

Again, what this chart is saying is that if we took the same physical area (Toronto's 630 square meters) and just increased the population density to that of, say, Paris, we would then have a total population of over 13 million people and we'd be housing an additional 10,011,573 humans on the same footprint.

I am not suggesting that this is exactly what should be done. (Though, you all know how much I love Paris.) What I'm suggesting is that calling a place "full" isn't exactly accurate. How would you even measure that? What someone is really saying is that they are content with the status quo in terms of built form and density.

Note: The above population densities were all taken from Wikipedia, except for Toronto's figures, which were taken from here.