>>13987881 (pb)

Experimental Concrete would be my guess. Florida has been doing it for years. There was a walkway collapse that sent me digging into it a couple years ago. It was made of some Carbon absorbing shit.

That would be my educated guess of what caused this collapse. The Romans mastered it 2000 years ago and we keep thinking we can better it. Yet our shit crumbles within 50 or so years.