Re: Ancient technology ...
I suspect the Roman empire was responsible for holding back, or even reversing, the development of science and technology over a large part of the 'old world'.
I vaguely recall reading somewhere - perhaps in A History of Pi? my copy is on another continent at the moment, or I'd try to find the passage in question - that the engineers of the much-vaunted Roman aqueducts thought water flow was proportional to the radius of the conduit, rather than to its cross-sectional area1 (neglecting edge effects). The suggestion was that Roman engineering mostly consisted of "I dunno, try making it bigger" rather than actually doing the math.
But I haven't looked into the matter at all myself.
1And thus to the square of the radius.