[Geckorian]

I can see where extreme hills or taiga could make for a nice biome for a medieval city. Plains would be easier to build on. If you want historical accuracy, a vast majority of the oldest cities in Europe are built on either swamps, marshes, or the intersection of river ways along forests. Personally I would suggest looking for a Dark Wood forest near a taiga or extreme hills area. Much of you build will likely use dark oak or spruce for wood and finding a spot with these two biomes near each other (hopefully near a river) would give you access to at least 4 types of wood to work with as oak and birch are also found in dark forest biomes. If these two biomes butt up against a plains or flower forest, so much the better.