Troubles when designing a Major city in my world.

[Mongobear]

So, I have started to design my campaign worlds capital city, and I have encountered a pretty major issue that I sort of am unsure if it would actually even be possible.

In my original write up, the capital city is built into a shattered mountain on an island in a bay approximately 25 miles off the coast of the main continent. As of right now, I had the dimensions of the island roughly 3/4 of a square mile, and seperated into approximately 200 100ft squares for each block/district.

It is designed sort of similarly to Minas Tirith from the LotR movies/novels in a layered fashion with the lower classes at the bottom, an the richer areas and wealthier citizens on the higher levels.

Now, this is the part that gets kinda of outrageous, using the DMG/DMG2 rules for populating a city, the population of this city should be anywhere between 300k-900k people, depending on how i distribute each districts population and features. Is that even possible to fit that number of people into an area that small? When I calculated i using the book rules for population density and space required per person I would need a city nearly 4 times the size as the one I made, or have nearly every residence in the city be atleast 3 stories and multi family, which is doable, but that even accounts for the Slum and low class districts, which wouldnt be able to afford to build that many large buildings.

I know as the DM, I can just say these structures exist and everything works because I said they do, but I generally like to keep things as close to by the book as possible, and cramming half a million people into an area less than a square mile doesnt seem like it would be feasible. Did I miss something using the city building rules? did I do my math wrong? or should I rescale the city map and make the island much larger?

[Cruiser1]

I had the dimensions of the island roughly 3/4 of a square mile, and seperated into approximately 200 100ft squares for each block/district. Now, this is the part that gets kinda of outrageous, using the DMG/DMG2 rules for populating a city, the population of this city should be anywhere between 300k-900k people, depending on how i distribute each districts population and features.
There's 5280 feet per mile, so 3/4 of a square mile is 5280 x 5280 x 0.75 = 20,908,800 square feet for your island city. 300K people means only 70 square feet per person, which is less than three 5 foot squares per person, which is really small! Real world cities rarely exceed 10K people per square mile (http://www.infoplease.com/ipa/A0934666.html).

In DMG2 p107, it says even crowded cities have 1000 square feet per person. That means your city should only have 21K people total (and it would still be considered "crowded"). To have a crowded city of 300K people, you need a larger area of land 3.2 miles on a side (over 10 square miles).

One way around this is to have a vertical city like Sharn in Eberron with its mile tall towers. You could do something similar by having much of your city inside the mountain, meaning there are many floors stacked on top of each other. If the average place in your city has 14 floors, then you could fit 300K people in 3/4 of a square mile, and have 1000 square feet per person. :smallsmile:

[Red Rubber Band]

It is definitely possible (https://en.wikipedia.org/wiki/Kowloon_Walled_City#Population) to fit that many people into such a small space. Though that example is more modern than I assume your setting to be.


Now, this is the part that gets kinda of outrageous, using the DMG/DMG2 rules for populating a city, the population of this city should be anywhere between 300k-900k people, depending on how i distribute each districts population and features. Is that even possible to fit that number of people into an area that small? When I calculated i using the book rules for population density and space required per person I would need a city nearly 4 times the size as the one I made, or have nearly every residence in the city be atleast 3 stories and multi family, which is doable, but that even accounts for the Slum and low class districts, which wouldnt be able to afford to build that many large buildings.

This is the part that confuses me. It looks like you used the books rules for populating a city, and then did another calculation using the books rules for population density and came up with a different answer for how big your city should be. Is that correct?

Minas Tirith is several stories tall. So perhaps your calculations are thrown off by not taking that into account in one/both of your calculations?
Slums and lower class disctricts may not have to afford to have the whole building built. The ruler could have built them - and maintain as they will be at least partially supporting the rest of the city - and the residents need to pay an extra tithe to live there.

[Mongobear]

This is the part that confuses me. It looks like you used the books rules for populating a city, and then did another calculation using the books rules for population density and came up with a different answer for how big your city should be. Is that correct?

I drew the map scale independently of creating the population and district distribution. I didnt realize the book actually had minimum populations for each district type until after the map was drawn, and the scale was set, which is why i started to do the math on it and got these crazy numbers.

Going as far as just rewriting the map scale to accomodate the required population is doable, and the easiest fix, but im just wondering if maybe i math-failed somewhere and added an extra digit or two to my calculations.

[BowStreetRunner]

The real question is: will your PCs even notice? I do not ask this sarcastically either. In most of the games I have played the DM was able to get by with descriptions of what we saw (the streets are crowded with people) and rarely went into as much detail as the actual population. In addition, while there are many examples of ancient to medieval civilizations attempting a fairly accurate census, there are as many that did not. So even if the PCs ask in-game, they are not necessarily going to get an accurate number.

My recommendation is to get the numbers to where you feel comfortable, but don't dwell on it too much. In the end, whatever you feel is right will likely suffice.

[Mongobear]

The real question is: will your PCs even notice? I do not ask this sarcastically either. In most of the games I have played the DM was able to get by with descriptions of what we saw (the streets are crowded with people) and rarely went into as much detail as the actual population. In addition, while there are many examples of ancient to medieval civilizations attempting a fairly accurate census, there are as many that did not. So even if the PCs ask in-game, they are not necessarily going to get an accurate number.

My recommendation is to get the numbers to where you feel comfortable, but don't dwell on it too much. In the end, whatever you feel is right will likely suffice.

I think im going to fudge the numbers a bit, and get them to a reasonable, but still claustrophobic number, something like 50k to 75k people in the city, since now that ive reread the books, most of those numbers are accounting for travellers and other temporary residents, not permanent citizens, and I didnt even think of having underground areas, I can have an Undercity of sorts for many of the undesirable sorts or Dwarves.

[BowStreetRunner]

...I didnt even think of having underground areas, I can have an Undercity of sorts for many of the undesirable sorts or Dwarves.
If you really want, you can do much more than that, considering the diversity of the 3.5 Monster Manual/PF Bestiary. You said this is in a bay, how about some underwater dwellings for the merfolk and other aquatic races? A city amidst shattered mountains would be nice places to construct not just tall buildings for humanoids, but also eyries for Raptorans and other flying races. Or how about large Redwood-like trees rising up on the slopes of the mountain, each with a spiraling wooden 'road' climbing up its sides, every such towering edifice home to thousands of sylvan creatures in homes clinging to the trees while trying to adjust to city life. Don't forget that strange 'park' near the center of town that always seems dark even during the day - it's actually connected to an Illumian-build expansion to the city that actually exists on the plane of shadow. The entire section inside the Shadow Gate is a quarter the size of the portion of the city on this plane and is a thoroughfare for creatures from throughout the planes.