The Medieval Fantasy City Generator

It’s like Uncharted Atlas, but for cities: the Medieval Fantasy City Generator is a web application that “generates a random medieval city layout of a requested size. The generation method is rather arbitrary, the goal is to produce a nice looking map, not an accurate model of a city.” As was the case with Uncharted Atlas, the effect is accidentally damning: if an algorithm can create a fantasy setting indistinguishable from a human-made product, what does that say about the human-made product? [Ada Palmer]

Previously: Uncharted Atlas.

Uncharted Atlas


Uncharted Atlas is a Twitter bot that generates a new fantasy map every hour. The brainchild of glaciologist Martin O’Leary, it uses algorithmically created terrain that is weathered by water erosion, a process he details on this page (All Over the Map’s post explains it in more human-readable terms). As Martin writes:

I wanted to make maps that look like something you’d find at the back of one of the cheap paperback fantasy novels of my youth. I always had a fascination with these imagined worlds, which were often much more interesting than whatever luke-warm sub-Tolkien tale they were attached to.

At the same time, I wanted to play with terrain generation with a physical basis. There are loads of articles on the internet which describe terrain generation, and they almost all use some variation on a fractal noise approach, either directly (by adding layers of noise functions), or indirectly (e.g. through midpoint displacement). These methods produce lots of fine detail, but the large-scale structure always looks a bit off. Features are attached in random ways, with no thought to the processes which form landscapes. I wanted to try something a little bit different.

The code is available for playing with, and apparently other people are doing just that. Another algorithm—one that linguists should find fascinating—generates the place names.

These maps, generated by Python and JavaScript, are at least credible in comparison to the human-made product. (Quite possibly better, since fantasy maps aren’t always geologically and hydrologically accurate.) So it’s possible to look at Uncharted Atlas as an indictment of fantasy geographies and maps.