Copper tarnishes quickly and forms a green patina in salty sea air, and the vast majority of ancient settlements happened to be on the coast.
I live in an older town about 700 miles from the ocean, they recently restored our courthouse with a new copper roof to replace the one from 1824 and it had a green patina in less than a year.
I don’t think salty air is a requirement for patina, just oxygenation.
Every spider you kill that you see makes them better at hiding in your house