Quote Originally Posted by NeoSpartan
The knowledge of how to do it was lost, as well as the knowledge for interior pluming, aqueducts, stone roofs, arches, etc. etc. It was all "rediscovered" in the centuries following the Dark Ages. Exept plate armor used Riveted Plates instead of Leather to allow the wearer to move.
He has a point the dark ages were called the dark ages for a reason. Alot of stuff was forgotton probably including the knowledge of how to make certain types of armour

And although exact dates are debated it is pretty much agreed that the roman empire began its decent long before 200 AD.