There are many things one can infer from these civilizations just by
knowing that they were able to build such massive structures. One was
that they had a running civilization which was able to provide for its
citizens in adeqaute amount - this allowed them to be able to undertake
such feats.
Another thing is that we know they had the necessary
knowledge to actually build such structures - this tells us that they
were relatively advanced for their age and time.
Another thing
we can know from this is that they probably valued some sort of rituals
and had people who were at a higher level in society who also commanded
for these structures to be built.
