Damascus Steel

We have this notion of history as uninterrupted progress. It isn't, of course. Europe regressed between 300 CE and 1000 CE; the Americas are littered with the cities of civilizations that rose, thrived, and collapsed even before the Europeans arrived on the scene. (And not just the Toltecs, Olmecs and other Meso-American empires; check out the Moundbuilders on the Mississippi. Much respect!)

Damascus Steel Blades

The notion of progress is itself pretty new. The Classical Greeks saw history as cyclical. Medieval Christendom believed history was divided into three parts - before Jesus, his ministry, and then everything after - bounded start and finish by the Garden of Eden and the Day of Judgment.

So the fact that our predecessors knew how to do some things that we still haven't figured out shouldn't be too surprising.

That's not to say that the Egyptians had space travel, or the Mayans could predict the future. It just means we haven't recovered the processes by which they made things like Greek fire, layered stained glass and Damascus steel. (Of course, napalm does make Greek fire seem a little old hat.)

And for the really impressive pre-industrial stuff, check out guys like Heron of Alexandria.