A process that began with an educated guess, this I suppose to be an early expansion of the initial perspective. It is a fun challenge (thought experiment), one piece of a puzzle is key to the others though more-so to specific aspects of the undetermined set/values.
This also means that if limestone construction is proven exact, we could begin to express how the Pyramids were built. This would also cause an issue for those who published the perspectives this might falsify. The most interesting, "painting a picture" of life during the construction of the Great Pyramids at Giza. Filling in the picture puzzle based on educated guess, what would seem more logical than the current interpretation. A perspective that is being explored till proven false.
Cement has a "compressive strength" value. Cited from data concerning high-limestone content in cement mixtures. This helps...
https://www.zkg.de/en/artikel/zkg_Limestone_requirements_for_high-limestone_cements_2547698.html
"..and no others, from time to time at all time during the term of years therein expressed, should and lawfully might make, use, exercise, and vend, within England, Wales and the Town of Berwick-upon-Tweed, my invention of "AN IMPROVEMENT IN THE MODE OF PRODUCING AN ARTIFICIAL STONE;" in which said Letters Patent there is contained a proviso obliging me, said Joseph Aspdin, by an instrument in writing under my hand and seal".
..now I understand that I did use the correct nomenclature for pre-modern cement, Faux-Stone.
https://en.wikipedia.org/wiki/Joseph_Aspdin
We can notice in the title declaration of the patent "AN IMPROVEMENT...". This tells us the English inventor improved upon a technique which existed at the time. This suggests there are earlier applications of limestone construction... more research.
THIS SETTLES IT (keep collecting puzzle pieces for now). Not only did the Roman's possess the technology, they were applying it more effectively than we apparently. 
What if, hydraulic lime does not objectively qualify ancient limestone construction? ..might we study the earlier iterations of the technology by performing an experiment. Bricks can made from fine sand aggregate. If these yield a building material with sufficient properties, an "accurate to scale" 2.3 ton Pyramidal block can be reproduced ..at a North American University? ..approximately fifty volunteers will be required to demonstrate that 5000 lbs might be moved by the summing of human cooperative forces [50 multiplied by a factor of 100lbs].
A franc-macon once published in the forward of his edition, "..after 10,000 years all traces of a civilization no longer exist". With that information, the book begins.
The book provided details of South American pyramids. Significant expansion concerning La Porte du Soleil was also given. Hmm... La Porte du Soleil ..Door to the Sun. Why the post-megalithic obsession with the Sun? ..was the planet warming? ..shades in style for several millennia? ..maybe they intuited that the center of the Earth is warming till it resembles the source of convergent force that finds itself expressed omni-directionally about the core of the solar satellite participating in the converged state of the possible system ..nah.
Do you think ancient cultures were aware they worshiped a ball of plasma in the sky? ..and where do we take ourselves with this information?
..even more cement, who turned a blind eye? ..fancy red cement this time.
OMG! ..look, the elephant ..not an ELEPHANT! ..a possible megalithic construction vehicle, the Mastodon.
Just because they were large does not require them to be hostile creatures.
Which site used more water, Giza or Tiwanaku? ..porosity, a hydraulic footprint.
The experiment I have proposed has long been completed, successfully. The team even reproduce the layering noticeable in deteriorating blocks (tamping layers). 
When artisans displayed their proficiency the production of thin and more decorative pillars seem to be a trend.
I am not sure how to feel about all of these great ancient sites being concrete. It is amazing, logical ..not exactly disappointed ..I feel as though I have "entered the egress".
What if it "gets around" these are made of concrete? ..will that affect interest and tourism?
To me they are no less impressive and timeless.
As far as aliens and spaceships are concerned, I believe that humanity has always had the dream of sitting near the fire at one of those far away villages in the sky.
Who needs to be right when logic intends that we are correct. Debate can proceed.
If both are attempting to be right, they are necessarily incorrect.
The handedness of a response should not be argued so often yet illogic persists due to bad mentoring in media.
Apparently ancient civilizations made concrete (faux-stone) the way we implement ashphalt techhnology, using compression (tamping). Our modern concrete requires more water, a much "soupier" business than the historical iterations from which it was elaborated.
Pyramidal chamber vault blocks (ceiling). "Can the builders make the Pharoah a bad pyramid block? ..only solid enough to hold the setting block atop it."
A visualization of Minecrafters and Pyramid builders.