Urban cohabitation with dragons is going to be a difficult challenge. I don't think you will be able to maintain traditional fantasy "urban" dwelling while also having dragons.
Anything that is a couple hundred feet long is going to weigh at least a few tons. All but the strongest stone structures would crumble under their weight. And dragons are going to need a lot of space to spread their wings and take off (physics notwithstanding). This means you are going to need to have massive open spaces, or super-strong buildings that allow the dragons to take off from above the skyline.
I'm also assuming, by cohabitation, that dragons will purchase and maintain dwellings of their own. Even if they are content to live in stalls like cattle, those stalls would have to be huge. If we provide dragons with the basic domestic comforts, like beds and kitchens, we are talking about massive enclosed spaces. Steel would likely be required to build these buildings, as wood and stone wouldn't be able to span the couple-hundred-feet required for just the dragon's bed, not to mention enough space for them to turn around in.
I'm assuming that, by cohabitation, you also have dragon services provided, like food and sanitation. Dragons, being as large as they are, will require a tremendous amount of food to survive. A single dragon's food requirements will probably be larger than those of a neighborhood. This will dramatically increase the food infrastructure.
Along with lots of food comes lots of waste. Assuming dragons have massive latrines, someone will have to clean those, and dispose of the waste. Since dragons are likely meat eaters, their waste would be especially smelly, and a breeding ground for dangerous bacteria.
Jobs and shared spaces
It's very difficult to imagine a dragon and a human working side-by-side when the former out-sized the later by a couple orders of magnitude. Shared spaces, too, would be dramatically different: a large human park wouldn't even be enough space for a dragon to nap in.
Even if dragons are in charge, there are menial tasks that would likely require non-dragon assistance. In the courthouse, for example, you probably wouldn't have dragons doing all the basic tasks, like security and check-in.
The difference in size and needs would make it difficult for these two cultures to mingle: you would have to have dragon jobs, dragon parks, dragon homes, dragon food, and dragon sanitation, all while having human jobs, human parks, human homes, human food, and human sanitation. At best, I believe that you could have a human and dragon city side-by-side, with some shared services, but complete integration seems unlikely at best, and foolhearty at worst.
Even simply accommodating dragons in a non-dragon city would be difficult. Their size alone would make all but the most trivial contact all but impossible, or it would require a dramatic infrastructure change for little benefit to the non-dragons (much stronger buildings, much wider roads, much wider open spaces, etc.)