This city was originally created for my homebrew D&D campaign. This is how I thought it through:

1. The large fortress on the northern side of the river is an entrance to an underground city. For example, dwarven or drow (how you like).

2. The mighty bridge connects the underground city with an "old town" (red roofs). This district was built by the people of the underground city as a trade outpost on the surface.

3. Later, due to political or economical reasons, the surface town became independent, and new settlers brought their architectural styles to the city.

4. Now it's a city of trade and prosperity.

5. Western districts (by the river bank) are less involved in trade and more into fishermen business.

6. Farms are on the southern part of the city.

Please, feel free to use my map for your campaigns as you see fit. I wish you many pleasant hours with your D&D group.

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