The Gravitatias of the Past

There's a popular idea that we don't know how to do these things nowadays. The aliens knew where did this knowledge go? Also, there's this thing, I think it's called the cathart or something like that,. which is this idea that there was this ancient civilization and there's still evidence of it today. And they built buildings. But you could not show us a single building throughout history. Modern technology and engineering could not also build... It's laughable.