Who Created This Mysterious Structure Hidden In The Rocks? 

Researchers have done the math on the time and tonnage of material it would take to create these structures. Virtually impossible to move this amount of material with hand tools. and the rubble, in many cases, can’t be found. We couldn’t accomplish this with modern equipment. Thus, the mystery.

@@mr.c2485 Very true. Many technologies have very clearly been lost to the past. Human technologies. Most of these structures actually have likely hypothesis as to how they were built. But yes, we don't know for sure. The ancients did a surprising amount of stuff better than us. Even simple, elementary building material like concrete was much better in the antiquity (Roman concrete). But I do believe that we don't give our ancestors enough credit. They were clearly perfectly capable of creating amazing stuff. Stuff which can only be built by a society which can mobilise its population for these purposes. With enough people power and time, amazing things can be achieved. Things we just can't do today...or just have no reason to do.

@@ivareskesner2019. I also feel that many of the actual technological tools were deliberately destroyed.

@@rhoward295 Definitely. For political reasons and all throughout history. The only reason we have anything to research at all is because the things we have were all hidden.

I concur with your postulation

Mammoths

I'm sorry but I found your comment devoid of any meaningful criticism. Surely you could have communicated your derision more concisely so as to have an impact on Katrina's future videos.

@@Dan-ow5es btw are you dense and never seen good content? Damn I said that the content is bad because it is devoid of anything relevant... So please don't think that I'm being harsh just for the sake of it...