Current questions and answers regarding the map editor.

Nothing prevents you from creating your own city (except for a small amount of experience). In it, for example, half of the buildings could be human, and half could be orcish, and you wouldn't need to build anything for the capitol or castle.

Added 3 minutes later
But specifically, creating your own city is already modding, and questions about it should be asked in another thread, and to other people, such as psaktha or zahar0z.