Theory: Urban Fantasy

Urban fantasy is a sub-genre of fantasy. One of its main characteristics, as the name suggests, is that it is set in an urban environment, typically a city. Unlike some fantasy storylines set in the wilderness or on alien planets, Urban fantasy comes the added storylines of social etiquette, political complications and all the social implications that come with Urban living.

An example:

“If Jon slays a witch in the middle of the wilderness, and no one hears her fall, there aren't any consequences for Jon. On the other hand, if Jon slays Morgawse, who happens to be the mother of King Arthur and of his son Mordred, not to mention a political force in her own right as ruler of Orkney, Jon must deal with political and emotional fallout. If he hides his deed, he must worry about discovery; if he flees to France and from there across Europe to the Holy Land, he'll have adventures along the way; if he sticks around and boasts of his prowess, he earns Mordred's wrath and puts Arthur in a difficult spot.” 
(http://www.writing-world.com/sf/contemporary.shtml)

Urban fantasy can come in many different styles; aliens invading modern cities, mythological creatures invading settlements, alternate universes where magic and civilisation live in harmony, modern times where the magic community live in hiding unknown to most people. A popular example of the latter is Harry Potter where wizards, witches and monsters live unnoticed by ordinary humans but dwell among us in hiding.

Urban fantasy does not have to be confined to modern cities and times however. Authors Marie Brennan and Cassandra Clare have been known to use urban fantasy in Elizabethan and Victorian settings. It is still Urban Fantasy because of the location it is set and the social implications that come with it.

I have looked at Urban Fantasy as a possible setting for Charn where the white witch used to live. The back story of Charn could be that magic, monsters and witches lived in plain sight of ordinary life. So when I design the sets for Charn I could have dead people, monsters and wizards all in the same place within the city, as if magic and monsters was the norm.