That structure’s interesting because the roof is basically one giant stone, probably the largest ever used in construction in Italy, and maybe anywhere. The Romans quarried some single-piece 200 ton columns in Egypt and transported them by ship to Rome for some temples, that’s the only things that come close.
Oh, the Baalbek stones are much bigger than this, and technically they’ve *been* used in construction, but their original purpose remains unknown, and they’ve had stuff built on top of them, I mean, wth else are ya gonna do with ‘em?