Hmm. Yeah, I guess Civic Centers at least, maybe barracks and stables (anything military, TBH). Houses should just be capturable flat-out, same with any non-Civil Center civic or economic building. IMO fortresses should not be capturable at all, only destroyed (I know that doesn't really fit with history, but it would make the game more challenging).
To make it effective, some other ideas(features) are needed, such as damage from units with torches. Therefore, there would be fire damage, the capture doesn't necessarily need to be 50%, and not necessarily all buildings.