Howis it we lost so much ancient technology?

Steven say: No. Perhaps you, and those making sensational "ancient alien" shows can not believe that ancient people knew things you don't, but that does not mean educated people don't. Every time you hear that modern science does not understand the work of people in the past, it is a given you are being lied to by con men. Most things like the pyramids are not repeated because educated people understand what a bad idea they are. We know the pyramid builders did not understand the constant pi, because they used a wheel to measure distance and did not compensate for it, resulting in the number appearing in the ratios of their measurements.
-
JG say: Define "ancient" please.
-
Philomel say: We have not lost any ancient technology. There is nothing they did that we cannot do. We don't know how the ancients did some of the things which they did but that does not mean we can't do them.
That is not lost technology but rather lost methodology. If we need pyramids we can build them.
-
Adam D say: Please elaborate about what technologies have been lost specifically.

EDIT: We know how the pyramids were built, we could replicate them today with primitive technology - or much faster with modern technology.
-
Colin say: Please list the achievements mentioned in your update.
-
Choose a bloody best answer. It's not hard. say: Like what sort of things?

Egypt fell, Rome fell, China closed its doors. The knowledge was lost to later ages, but rediscovered. For much of that rediscovery we must thank the Arabic civilisation.
-
CarolOklaNola say: War, time, floods and erosion. The Romans burned the library at Alexandria Egypt, maybe not intentionally, but even without war. natural processes like erosion and floods and technology becoming outdated and unusable can make knowledge inaccessible.. i have the text of my master thesis on 3.5