I expected something much simpler : bricks, stones, and wood. It's not like we are running low on examples of 1000+ years buildings ( https://en.wikipedia.org/wiki/11th_century_in_architecture ). These castles, cathedrals, farms, were built to last, so it's appropriate to use them as examples. We can, however, apply modern technics and materials when they make sense : insulation, windows, waterways... Prefer wood, wo…
What is behind your thinking that plastic won’t last? Plastic is estimated to take 1000 years to decompose in landfills. Obviously it did not exist millennia ago, but I wouldn’t write it off as not future proof. I too have a 200 year old house and the sagging mentioned in the article seems inevitable in wood.
even if we understood plastic to retain its original qualities over time, it is impossible to speculate about a thousand-year lifetime. it's unusual to come across any plastic a hundred years old, intact or not.