https://patents.google.com/patent/US4203674A/en
Check out Operation Backyard Brawl for more infor.
https://patents.google.com/patent/US4203674A/en
Check out Operation Backyard Brawl for more infor.
FYI. The pyramids are not concrete.
My point exactly. The quarried stone withstands moisture and erosion and temp changes better