I've done it to myself.. I have created a fantastic city that I have to try to map now.
There is a canyon that is 100' across. The city is built 50' tall walls between the two sides of this canyon. So, now I have to design this city. (before anyone asks, yes I need to map it out, both for myself and to guide me as the PC's try to sneak through a seige and enter the castle unawares.
Does anyone have any advice on how this would be done? There castle has a regular population of about 500 people.
edit: sorry, it was clear in my head. The castle takes up the entire span between the two cliffs, and is 50' tall. There is another wall at the back, and the city is build between these two walls, but there are multiple layers to the city like a castle.