High-tech concrete technology has a famous past
Almost 1,900 years ago, the Romans built what continues to be the world’s largest unreinforced solid concrete dome in the world—the Pantheon. The secret, probably unknown to the Emperor Hadrian’s engineers at the time, was that the lightweight concrete used to build the dome had set and hardened from the inside out. This internal curing process enhanced the material’s strength, durability, resistance to cracking, and other properties so that the Pantheon continues to be used for special events to this day.
http://www.freerepublic.com/focus/f-chat/2690198/posts
we should have hired non-union Romans.
True. The Romans also invented the water mill, although they never made widespread use of it because they had slaves to do the heavy work.
So it wasn’t really developed until the middle ages, mostly in monasteries. That was the basis of industrial and technological development for more than a thousand years, until it was finally replaced by the steam engine.