Cities don’t just happen, though it may look that way to those who live in one. As a GM/world-builder you can “do it that way” (they just happen), but I prefer a believable world, which means that cities must have reasons for being there. For this article, a city is a settlement much larger than others locally, but it can also apply to towns.
Centers of Trade and Protection
Cities sometimes arise at locations that are natural hubs of trade. If patterns and routes of trade change then a formerly prosperous city can be reduced to a hamlet or less. (See also "The Cost of Trade")Cities are also hubs of agriculture. Specialists within cities provided services that a village could not support. In preindustrial times, cities were surrounded by a network of villages providing food for the city-dwellers. Keep in mind, land transport was expensive so food-producing locations needed to be close by or on a good transportation route, such as a river or sea. Some famous cities had their own seaport several miles away, like Ostia for Rome and Piraeus for Athens. Athens actually had miles-long walls connecting it with its seaport, while Rome was on a river that emptied into the Mediterranean at Ostia (which is now somewhat inland, owing to silting up).
Really large cities almost have to be on trade routes to help make provisioning (“the action of providing or supplying something for use”) the city possible. A city is often a center of production. People in a city rely on those out in the country to grow enough food, so that the city-dwellers can do something else (productive, we hope). The evolution of human history includes improvements in agriculture to the point that many people can concentrate in one place working on something other than farming.
Thanks to production and trade, cities are centers of wealth. In Roman times, the much older eastern cities were not only more populous, they were wealthier. Some scholars have suggested that the East Roman Empire survived when the Western Empire fell, in part, because of the greater population and larger, wealthier cities of the East.
Other City Origins
We can think of other reasons for cities to arise. Holy cities, for example, often existed before their religion, but became even larger because of their religious significance.Pre-modern cities are also population sinks – places for disease. People tend to migrate to, not from, cities, but disease holds back the actual population growth. Disease is less likely to spread through rural areas – not many people to carry disease from one place to another, and typically very little movement of people in rural areas. Further, at least in modern times, people living in cities are likely to have fewer children than those living in rural locations.
Population Limits
The practical limits on city population size are related to transportation, though in a fantasy world the limits may be different owing to magic and fantastic transport creatures. Insufficient transportation meant starvation (See "Medieval Travel & Scale").How big was a really large city in the premodern world? Rome itself was only about 50,000 people at the time of the Second Punic War (264-221 BCE), a city built of wood, but it later became closer to a million and was a city of concrete and stone. (There were lots of Romans in the Republic, but a relatively small proportion lived in the city; in the Empire five centuries later, vast numbers of inhabitants of the city had no jobs and were there for the dole. Much of late Roman strategy revolved around providing food for hundreds of thousands of dole recipients.)
How does a city become the capital of a large country? Start as capital of a smaller one (e.g. Thebes of Upper Egypt)? As we can see from American states, the capital is not always the largest city or even a large city (Lansing MI, Tallahassee FL). Fayetteville, NC was the capital before it was moved to Raleigh. A lot of it is accidental, really.
Cities can become legendary for many reasons. “Miklagard” (The Great City, Constantinople) was legendary for the Vikings. Rome is “The Eternal City.” I even remember reading James Blish’s Cities in Flight series where “New York, New York” was legendary in the far future. (Written when New York was the most populous city in the world.) In typical RPG play, there may only be a small village or town nearby, with “The City” a long way off, perhaps as legendary as Miklagard. Big cities are vastly complex; RPG campaigns are probably easier to deal with if set somewhere near a frontier rather than in a great city.
City-Building in Practice
In a fantasy world, better transportation can make a difference to where cities are, and their population. So can differences in agriculture. Non-human species have differing characteristics that will change the shape of a city too. Whatever your approach, thinking about why and how a city grew to its current size can go a long way towards making your fantasy world feel real -- and a place where many people choose to live together.Your Turn How do you plan out cities in your campaign?
It's a very, very bad place. But, again, looking at Australia, you don't have a trade center that only trades with Australia. Sydney is a major port because trade LEAVES Australia. You would not send goods from Perth to Adelaide by way of Sydney, obviously. But that's what's expected in Scarred Lands, because Shelzar is meant to be the "center of trade".
