Reading a history of the late Roman empire by Peter Heather. Enjoying it, talks a lot about the economy etc.
As an aside he tells us that the marble mines all pretty much closed down in the 390s. Constantine has gone Christian 60 years before, but paganism still thrived. And it was really only in the 390s that all the pagan temples got pulled down leading to a glut of second hand marble on he market, thus to the closure of the mines.
Sorta like what’s happened to the US steel industry really. So much scrap is now recycled that many of the blast furnaces have closed….