It is an interesting thought, but I think your example doesn't work. In that we have two complete halves in need of minor repair. For ruins, we have parts left, and don't really even know for sure what it's supposed to look like. I mean, a very good idea, but not for sure.

And especially, over time, you can end up with a bit of a ship of theseus.

Also interesting -- if some day one of the earthquakes there knocks down part of the colosseum, will we rebuild the ruins to their ruinous state?