No doubt, the less complex option is to transform an already existent world MTWII file. We save ourselves from thousands of calculations and problems.
This is the principle:
To try to substitute each one of the objects for others of similar form and location.
It's a complex task, but feasible.
There are two important problems,
1) The size of the individual objects that comprise a city.
For instance, south_european_city_a has got 6607 objects, many of them are double, triple and quadruple (they are the objects damaged in different stages). That result in about 11982 different objects.
2) Almost all the objects have got collission volume, that allow the buildings to interact (to be avoided by the camera, receive impacts and be damaged...). As of today, no one has been able to build a new collission volume for a new object (readed by the game) ("worldcollision small table" is the problem), the only option is to use vainilla collision volumes (of any world file), or accept small imperfections and incoherences.
Inside each settlement (castles, cities, villas, fortifications...) there are some "empty holes" or "empty spaces" (TechTreeSlot) that allow us to position buildings inside them, they are .world files inside larger .world files.
Inside "south_european_city_a" there are 9 (4 generic, smithy, church, cultural_building_large, market, tavern). (We can change them).
Everything is in the World Modified thread, read this post:
http://www.twcenter.net/forums/showt...00#post3983200
Do you understand what I mean? Small chapel is manageable, there are only 36 objects and 89 individual objects.
Tell me what settlement is the closest to your objective, and let's get to work.
Dismount it with WEditor 8.0 , understand all of its objects, modify them and replace them.
I've done it on small scale. To redesign 11982 objects is a bit "complicated".