How did the Romans move the ten 800 tonne blocks uphill? And the three 1000 tonne blocks? Also why did they cut smaller blocks from an unquarried 1200 tonne block that was still attattched to the bedrock, if they themselves had intended to put that block into the foundations with the other 1000 tonne blocks...? If they did all this work too, why didnt they make a record of having moved the heaviest stone blocks ever quarries and moved by man, an amazing feat surely worthy to be recorded by one of the most scholarly cultures of ancient times, no? I personally don't believe the Romans were responsible for the aforementioned stones, let alone modern humans. It's likely that those stones were quarried and placed there much longer ago, probably more than 10,000 years ago in the times when other hominids existed, some larger and stronger and evolved in different ways, some probably capable to domesticating and using mammoths to pull and more large stones etx. Homosapiens probably didn't quarry and extract the 800+ tonne blocks.
We can't know for sure. All we can do, all of us, is guess, and believe in what we believe in having judged all possible evidence within the realm of possibility.