I'm slowly grinding away at a campaign setting idea for some hypothetical future game. Brief description of the setting: Refugees from a continent wide cataclysm have moved to the only safe area, a 50 square mile (maybe, could change) area on the coast surrounded by mountains. This area is mysteriously unaffected by the chaos storms raging on the other side of the mountains.

My question: How big should this city be?

The tech level is peak of Roman Empire-ish. I want to have urban adventures, and guilds and organizations, but I don't want Sharn, either. It needs to be big enough to feel big, but small enough to be believable as this crowded refuge.

A sub-question: What do all the people do? I need ideas on how such an isolated economy would work.

How much available magic can be used for food, water, and sanitation?  That is you main constraint on population density.  Can garbage be carted away and food and water brought in at prices the locals can afford?

What do all the people do?  They have to be able to gather raw resources, process them, and sell or trade them to other people for an effective economy.
The more effeciently the gathering, processing, and selling the larger leisure group you can have.  You are probably going to want a decent sized leisure group for many adventures.

You could have magic providing the basic needs so much of the population doesn't have to work, or not work more than 20-30 hours a week.

You could have most of the population focused on creating and or exploring inside the mountains or under the city.  If the city has been built upon the ruins of previous cities enough times you could have much of the population involved in plundering and or defending against things in the ruins of the old cities.

With zero trade you are severely limited economically and your civilization is on a timer.  Eventually you will overwhelm the local resources and die off if you don't practice strict population control or find a new place to get resources.  You are also likely to have significant lacks or shortages of many things.

Quote from: Xavier LangWith zero trade you are severely limited economically and your civilization is on a timer.  Eventually you will overwhelm the local resources and die off if you don't practice strict population control or find a new place to get resources.  You are also likely to have significant lacks or shortages of many things.

This is actually something I want to emphasize. I want to create a harsh government reminiscent of the New Crobuzon Militia (from China Mieville's books). The government has to maintain this strict order to keep the resources coming and the population stable.

I'm envisioning several small towns set outside the main city, functioning somewhat like farming/work camps. I would also have a large, tightly controlled forest area, and several small mining camps in the mountains. The city itself would be confined by some natural boundary, either a river, or the city is an island. The government would ensure that the city did not spread past that point.

I want to stay away from too much of a magical solution to resource problems.


Brainstorming jobs
* One thought I had was a job for unskilled folks. The Mage's Consortium in the city  drains energy from volunteers. They draining doesn't do any permanent harm (at least that's the claim) and simply tires the volunteer out. Basically, they get paid to sit around and feel tired.

*I think the fishing industry would be pretty big. What other kinds of jobs revolve around a fishing town, besides the actual fishermen? You need shipwrights and repair people, net weavers/makers,???

*The exploration of the outside world is just beginning, as the storms have only recently died down. So,there would be some adventurer services industry beginning to grow.

Quote from: Berger King*The exploration of the outside world is just beginning, as the storms have only recently died down. So,there would be some adventurer services industry beginning to grow.

I thought the storms were still raging, if they have died down then your likely to enter a economic boom as populations spread out into new area and start trying to claim new land and new resources.

The city sounds pretty crowded to me. Just thinking in terms of population a Roman Era city could support 100,000+ people, but it did require a lot of outside support and internal planning to keep it coherent. It also needed lots of entertainment. Some version of an Amphitheatre or Circus would be a central point IMO.

Quote from: Xavier LangI thought the storms were still raging, if they have died down then your likely to enter a economic boom as populations spread out into new area and start trying to claim new land and new resources.

The storms have died down, but they will still surge up unexpectedly. The outside is still very, very dangerous, so expeditions will be more like missions to mars. Dangerous and very controlled. Settlement won't be happening for some time, but exploration and scavenging would.

Quote from: JamesVThe city sounds pretty crowded to me. Just thinking in terms of population a Roman Era city could support 100,000+ people, but it did require a lot of outside support and internal planning to keep it coherent. It also needed lots of entertainment. Some version of an Amphitheatre or Circus would be a central point IMO.

This is a good point. There's probably not enough space for a Circus Maximus style arena, but there'd be some sort of venue. I could also  see a lot of underground bloodsports, just like the illegal gladiator fights in New Crobuzon. Also, there could be a significant theater/entertainer area, and there coud be conflict between them and the overbearing government.

I should have been more clear, when I meant crowded, I was thinking dense. If the main city in particular is considered safest, then most people would want to live as close to it as possible. So buildings would be either going up into highrises or deep down into underground warrens.

Heck why not both?

A Classical setting would have MUCH larger cities than a medieval setting, if we're talking Europe here.

The key difference was really one of sanitation; the Roman roads and aqueduct systems made it possible to have much larger cities than what was available later on.

In 100 AD, there were several cities in the Roman empire that had populations of over a hundred thousand. We know for a fact that around that time, the city of Lugdunum had a census that measured its population as being 100k.  Rome itself at that time had almost a million inhabitants, and would beat the million mark shortly thereafter.
Meanwhile, by 1000 ad, having thirty thousand people in a city made it a fucking metropolis.

Wheras in the arab world, you could have cities that were much larger, because sanitation and infrastructure was much better. In 1000 ad, the muslim spanish city of Cordoba was by far the largest city in europe, with somewhere between five hundred thousand (conservative estimate) and one million inhabitants.  That's more people than the current population of Cordoba today, btw (which is about 350 thousand).

RPGPundit

Geez, thanks for the perspective. The largest city in my fantasy campaign is like pop: 20,000, and I thought "I'm really kinda pushing it, aren't I..?"

QuoteRome itself at that time had almost a million inhabitants, and would beat the million mark shortly thereafter.

That's interesting.  I was under the impression that Baghdad was the first city to reach a million inhabitants around 900 CE.  From a reference that I cannot find at the moment (my Google-fu is strong, but I am lazy), the population of Baghdad reached around four million by the time the Mongols rolled through (read as: over) it.

Depending on the climate and available flora and fauna, rooftop gardens could provide some additional sustenance for families.  Terraces could be carved into the sides of mountains for use as rice paddies.  

How long has the city been this crowded?  Refugee camps aren't all that concerned with sustainability, sanitation, or productive labor.  Placing the civilization on a short timer in that regard could make for some interesting flavor as the residents become more and more desperate, and the government response more brutal, providing some incentive to participate in the risky expansion out into the dangerous, storm-wracked land.