[[[ForeverAlone]]]

Nothing can be confirmed so far. 
One thing for sure, there are highly advanced society before last ice age.

The structure is incredible heavy and expensive for current technologies.

This is why I always feel human timeline , historians seem miss cannot find that " missing link " it seem there is one period is missing.
I read before engineering using the present technology try to reconstruct a model of those ancient buildings just don't know why it hard to be accurate copy it. It seem puzzle. Imaging ancient day those people without present technology how on earth they can managed to build those ancient buildings, so details etc.