So being able to muster resources proves they are the work of an advanced pre-historic civilization or the work of aliens.
BTW, please let me know when you find a modern crane capable of lifting 750 tons of stones like those in Baalbek:
https://www.atlasobscura.com/places/baalbek-trilithon
Not aliens but lots of people, animals …. Another view is presented in Genesis.
Give me a lever long enough and I can move the world.