If the grid for the Exquisite Corpse City is going to be 30 foot/10 meter squares, I wanted to see if that really made sense.
So (perhaps prompted by Stephan Beal’s suggestion in a geomorph discussion), I got a Google map of Carcassonne and did a quick and dirty grid overlay with roughly 30’/10m squares. It looks pretty good to me.
This isn’t the full 20 x 20 section, but it is 20 squares wide (counting just the full squares), so it’s a reasonable guideline for medieval building density and what an Exquisite Corpse City section might look like. It’s tight enough in that it’s worth drawing from an artistic perspective, but, at the same time, it’s far enough out that lets each section be a substantial enough size to become a city map. People are pretty small at this scale, but are still individually distinguishable; it seems like a really good scale for something like this.
There are only a few roads in this at this scale, but roads, lanes and alleys can be distinguished. A one-square building is reasonably good sized, but there will be many features that are smaller, so drawing at a larger scale and then downsizing for the final drawing may be called for.
For a more visual reference, here’s what that same area looks like as an aerial view:
For another reference point, here’s a bit of Paris at about the same scale. If you want the aerial view, you should be able to find that on your own.