So, after too much time thinking about doing it (and doing too much worldbuilding while doing all that thinking), I have finally started to actually put lines to paper in the Black Blood of the Earth game. The starting location for the players will be the small, walled city of Belwick, on the edge of the empire (which is still unnamed). Belwick lies on a fairly large river (about 150 feet across where the town lies, I don't yet know what it is called), and has a population somewhere in the range of 6000-8000 people - I'll know better when I finish the map. The main part of the city is surrounded by a wall about 50' high and 20' thick, with 60' tall towers about every 200 feet or so. The most dominating feature of Belwick is the Tower of Grond, which is the location of the ruler of the province of which the city is the capital (there is also a city government). The Tower is about 300 feet across at the octagonal base, narrowing to a square about 100 feet across at the top, and rises a stunning 450 feet into the sky (about 30 stories).
Underneath the city is a sewer system consisting of underground passages that connect to each other and to some of the sub-basements in the city's buildings. There are also mysterious tunnels that connect to the sewers but are not a part of them. The players will start the game with a map to one of these tunnel systems, with rumors of treasures to be found in them.
And that's all I know for sure right now.