Here is my initial sketch of Oten'jo.
It is subject to change as I start working in an actual scale.
Some basic ideas I'm working with.
The castle is built into the base of a mountain, with the stone quarried to make the walls around most of the city. It will most likely have a moat that is supplied by the river coming out of the mountains.
The canal feeds from the larger river and dumps into the smaller river. (river police can call me on this)
The canal and the smaller river make natural borders for the various classes.
The majority of the farming is done across the river with a ferry system to carry grain across the river.
The samurai district is built on the sloping base of the mountain and a temple here is built into the mountain as well.
Well that is the most basic stuff, there are a few sketches near the top of the buildings.