When was the use of concrete developed?
2nd century BC
Who made the tools used?
metalworkers and carpenters
What tool was used to estimate straight lines?
What was water distributed into?
a system of pipes
Temporary bridges were built over what?
a row of boats
Stones were places in the space made by circles of stakes. What did these become?
What powered treadmills?
men turning it and pulling it
Where were stones larger in walls?
at the bottom
What filled the space between walls?
mortar and stones
When did the procedure to make walls repeat?
after the concrete dried