The other thing that they've not managed to control is moisture. You can't mix and match steel with lime mortar (I mean you can, but its not wise) You can just put a moisture barrier in there, but you need a way to maintain that (its not like a damp proof course, its far more extensive).
Personally if you want to make a house last 1k years, just make a clay lump house. It'll be far cheaper to build, look more realistic and much more well understood how to repair it.