Grand Hall was the capital city in my current points of light campaign. Here we have a a city that was once much larger and prosperous. With the decline of the last great kingdom, the city has suffered many more attacks. In addition, the lack of a unifying government decreased trade with neighboring communities. As population decreased and areas took damage, they were never repopulated and slowly fell into ruins and slums.
The grey is meant to represent ruins, and abandoned areas, while the other colors distinguish different styles of architecture in the city. I've include one with my notation and one without. Enjoy.