It’s funny how as soon as something is either invisible or disconnected by time from something else, it suddenly is a matter of belief for some people.
I’m glad we don’t hear debates about whether it is possible for an internal combustion engine to power a motor vehicle at highway speeds.
You think Hoover dam was built by humans?? No-one can build anything that big. The architects were helped by aliens.
Structure of that size placed so precisely that it happens to form an artificial lake and produce electricity?
Besides Hoover dam is a single structure. No seams or parts. What factory can produce a mold that big let alone move it across from factory to the river. There are no trucks that big.