Really? Aliens?

So at this very moment I am watching a documentary on Ancient building and possibility that it is built or people who built it had helped from aliens. And two statements that are a repeating theme are, "Why would people do things that are very difficult unless it is made easy by alien technology." Or "this is so difficult to do that even now we can not do it easily. So they must have alien technology help."

Let revisit the Renascence. Building huge dome, and arch are technology lost through the centuries. While ancient Roman and Greeks knows how to do it with perfection. a thousand year later, it's an alien technology. So really? anything we don't understand or can't accomplish, then that leads to it can't be done by humans? Talk about big egos.

Either way, i always keep an open minds about aliens and UFO's and ancient technology, but to draw conclusion base on our own stupidity, i really can not gad down. So to make a case and point you must give me more evident than they know more than we can give them credit for.