Blazing ahead - City placement

So, I haven't written anything for a little while. I've been busy. With other pressing matters, kids with the flu, but also with working on my project. I've experimented with several different themes, which except the base geography, creates very different effects. The outcomes are totally unique. I can like that! It means that some of the things that I set out to do are actually coming together. The greatest challenge in many regards is actually finding decent seamless textures! I'm no artist (which is part of the reason I started this project in the first place), so my own sorry attempts don't cut it.

After this "multi theme prototyping phase", I want to take a step back, focus on one theme, and create every map layer for that one theme. The next challenge is... drumroll

City placement

Cities and towns will be a layer of the map that you can choose whether to generate or not. I understand that not everyone will find automatically generated cities useful, - but I would, and as such, I'm doing it!

I'm currently in a phase where I'm trying to come up with a decent algorithm for finding suitable places for cities. I'm probably going to base it on the algorithm that finds river locations, with some modifications of course.

But I need your help.

What describes a good city location? Where are cities normally located? Cities might have different size, - can we generally say the likelyhood that a large city will form in a specific location? Or a small town? What should be the minimum distance between two cities, as a general rule?

These are questions I need help with finding the answers to, to create an algorithm that produces city locations that are believable. Take into account that the maps will seldomly be 21st century maps. Fantasy maps are most often of the  medieval sort, although they don't necessarily have to be.


I want to consolidate some of the major points written in the comments here. I am going to group the points made, into two groups:

  • Geographic
  • Sociological / Demographic 

In the Geographic group lies the most obvious and visible requirements.

  • "Near water" - probably the easiest requirement to check for. At a river mouth, a river fork, a bay, or a coastal point. 
  • "Mountain pass" - most likely not the largest cities, but strategically placed ones. Most likely very secure. 

In the Socialogical / Demographic group lies more indirect requirements that may have a large impact on the bigger picture.

  • "Trade routes" - smaller towns may form naturally along major city trade routes, especially if the area is lush and abundant with food.
  • "Cultural centers" - Harder to implement as an initial requirement, it could be interesting to attempt to plot major cities first, then perform a second algorithm, using the large cities as cultural centers, to sea how lesser cities and trading routes form in their vincinity. Implementing this is quite some way down the road though.

There are more things to consider, but unless someone suggests specific ways to put them into an algorithm, I think I have more than enough to start with. Excited!


  1. Cities form in locations that are good for trade, or strategically sound. Ports are good locations for cities. Positions on either sides of passes. Butted up against a mountain. At the forks of major rivers, or at the center of large trade routes. The distance between cities is based on terrain. In high mountain terrain or deserts the difference is vast. On lush ground, with access to water, probably not as much. People gravitate towards a major center though, so while towns and villages are not far from cities (often to supply them with the basic goods they need to thrive and can't produce themselves) they are not often multiple cities, particularly of the same size.

    I sadly don't have any concrete algorithms to suggest.

  2. Great points! Much appreciated. I'm going to update the post after a while, to include and reflect on the feedback I get. Again, thanks!

  3. I'd have to go find my old notes, but I did a lot of studying on cities at one point. There are 5 major things that a city needs (particularly a medieval city). Let me see if I can remember them:


    Hmmm. I'll have to post again once I get home to find my notes. I think one more is Religion, but I'm not sure. Government? I don't think that's right... Damn my brain and my new phone! (I had some of my notes stored in my old phone, but didn't copy them over, yet.)

    Anyway, any given city will have differing levels of the 5 necessities, but if one is missing, the city will eventually fail. Smaller settlements may form around even a single of these where it is really needed, but they won't grow to city size without all 5.

    There's a great book I got most of this from, and I can't remember the name of it right now, either... ;)

  4. OK, I found my notes (it was actually two phones back...)

    The five requirements are:

    Shrine (I knew it was religious.)
    Market (or general meeting place)
    Stronghold (less important in modern times, replaced by roadways)
    Housing (Duh. How could I forget this one?)

    Shrines aren't necesarily religious. There are cultural "Shrines" as well, and a royal court can provide some of that.

    Water itself is simple. However, rivers and large bodies of water can also provide roadways and trade opportunities, in addition to the basics. Also, with islands and canals, water can aid in security.

    I still can't find the book I got this stuff from. It may have been a library book...

  5. Awesome! Now I have alot of different points to work from! I'm going to update the original post, and consolidate note. Thanks!