I have been thinking about how things last.
Sometimes, things just stick around for a long time. The Romans, for instance, evidently knew how to build, since so many of their inventions and constructions persist through the centuries and millennia.
But I'm interested by the fact that some of the old places we've visited--medieval castles, Roman ruins and remnants--get picked up piece by piece, stones carried off, used for other things.
I remember being struck by this, that artists were recyclers, both metaphorically in terms of aesthetic ideas, and literally, in their materials. I saw a painting by Toulouse-Lautrec, I think, that had a whole other painting underneath it. These pieces by Andy Goldsworthy, installed in the National Museum of Scotland, use scrap wood salvaged from the construction of the museum, and slates rescued from demolished buildings in Edinburgh.