the use of inheritance would be well applied here. the main issue is developing an interface that provides all of the functionality you need while remaining generic enough to encompass all of the descendent classes. also, each class will have to make good use of encapsulation, since your map only knows that there is a CThingie on the tile, not that it is a CStoneWall, or CRock, or CTree. You may find that containing a number of internal variables, such as Durability, can accomplish keeping track of things like how decimated a stone wall has become, or how destroyed a tree is.

you may also have to come up with a base class for mobile game objects like catapult stones, arrows, or whatever, so that you can generically give an InteractWith() member function to your immobile object's base class.

so, anyway, there's MY thought.

***OOP- THE WAY TO BE***