The Collapse of Complex Societies, it's kind of dry but a very interesting look at the mechanics of societal expansion and contraction. He dispenses with a lot of popular notions of why the Roman Empire in particular collapsed with excellent clarity, but goes further than that and proposes a general theory of collapse that applies to societies of all types, even hunter gatherers. I haven't finished it yet however, and since I'm not particularly knowledgeable about archaeology or economics I don't know how well it fares against other works in the genre.