I’m back from Sicily, and it has been Greek, Roman, Arab, Norman, French, German, and Spanish before becoming Italian. Each civilization re-used whatever was bequeathed to it by its predecessors. That’s why you find a Baroque church incorporating columns taken from a ruined Greek theater and a Palazzo built partially from lava stones taken from a Roman villa.
I remembered a quote from Ellen Ullman: “We build our computer systems the way we build our cities: over time, without a plan, on top of ruins.”
We cannot see through the layers beneath our buildings in the physical world. That makes it hard to figure out if you can safely build higher. In IT, we can see the foundation. That allows us to know what changes we can make. As long as we have the source code and the people to understand it…