Ancient architecture and civilisation can be mind-blowing. It’s hard, at times, to wrap our head around quite how certain things were achieved by the people of the past- especially given they had access to such rudimentary tools! That’s led to an awful lot of rumination and theorizing. Is there a chance that extra-terrestrials intervened? There’s only one way to find out. Let us investigate! These are 20 ancient sites some people think were built by aliens!

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