Though the Umbra isn't as important in Mage as Aleph said I feel that the type of "Spirit of the City" is. Obviously the larger the city the more aware and potentially powerful/influencing such a spirit would/could be. Remember that the presence of a spiritually awakened city will leave its mark on many of the everyday facets of city life. Even if only for descriptive purposes.

Personally when i am the ST I run almost every town or city (and many important locations) has an awakened spirit of the location. Just HOW awakened it is, is based on my needs and desires as...