Also Concerning Forts, or How to Effectively Hide in A Flimsy Cardboard Box.

I am wanting a more in-depth fortification system than currently exists, and was wondering if anyone believes this is possible at all. It seems now that the forts in RTW are little better than cardboard boxes.

The idea is thus:
A family member builds a fort as normal, with his cute little army. But the next turn, while he is still in the fort, he is given the option of upgrading his fort. From say, a basic Roman fort to a motte and bailey. The next upgrade (if there is one at all) would, in turn, upgrade the Fort to a stone-walled, fortification.
These would of course be more expensive than the basic fort. If the basic fort costs 500 denarii, then the second upgrade (motte and bailey) would be 1000 denarii, and the third upgrade (stone-walled motte and bailey, or something) would cost an additional 2000 denarii. So, a fully upgraded fort would cost a total of 3500 denarii (500 + 1000+ 2000)
Of course the costs could be increased, lowered, et cetera.


Other fort lay-outs exist as well:

2nd level: Normal fort on a hill. Or just two series of wooden walls, one within the other.

3rd level: Perhaps a stone wall with open gates within the wodden walls. Or just a bailey with inner walls being stone (with open gates of course).

You can change the basic fort structure, but you can't add options to upgrade it unfortunately.

I wonder if you could have several different options of forts to build?

I think I read a post by someone who heavily modified a fort. It became a huge, huge spot covering almost the entire map and attackers had to fight their way in through a lot of the defensive buildings. Forgot what it's called tough, sorry.

Well, I am also looking for any sort of alternate fort, or well, anything regarding forts.
If you remember the name let me know. Or even screenshots. Anything will do.

Thanks in advance.