The article posted is very interesting. There are many questions as to who built these monuments and why. I am one to think the Ancients had contact with extraterrestrials thousands of years ago. After the bombardment of comets over 11,000 years ago (exact time not known, but this is an acceptable theory in mainstream thinking now) the survivors put the codes of contact into the monuments.
Ancient American cultures all learned by rote (memorizing) and never improved on what technologies they had. There was a down slide from knowledge after early ancient Egypt which is a mystery.
I do not think aliens built all the temples, but our ancestors did to show us who visited us and where they came from for us to contact them again.