Last year I backed the Hex Terrain Toolkit Kickstarter and have been working on a modular city layout ever since I got it.
Each Hex is roughly 15mm tall and 100mm from point to point. They have a smaller hex underneath that locks into a interlocking base so once they are all put together they won't move. That's not in any of the pictures yet.
The set is meant mainly to produce things like rolling hills and cliffs, which I will get to eventually, but I wanted to try my hand at making a modular city street first.
Here's a few WIP shots as I nail down the color scheme.
Once I get the basic streets done, I'll start adding multiple levels to do things like docks, canals, and entrances to sewers and catacombs.