One interesting thing to consider would be those cities which, for various reasons, have a mixed cultural heritage.  For example, (and this is an admittedly random example which presents itself only because I am traveling there soon) Qingdao, China.  This is a city which has, at various times, "belonged" to China, Germany, and Japan.  In certain areas of the city, the architecture is such that the city seems more German than Chinese.  In cities like this, you could mix and match the mythologies of the various cultures and even create a "turf wars" kind of scenario.  What do you guys think?