I live in a 130 year old house in Chicago. If you go in the basement, you can see the new foundation built on top of the old one when the house was raised, and

I live in a 130 year old house in Chicago. If you go in the basement, you can see the new foundation built on top of the old one when the house was raised, and how they added indoor plumbing at the same time. That being said, even though Chicago had high-rises at the time, buildings were all pretty much held in place by gravity at the time. Raising them was just a matter of having enough jackscrews to support the building and making sure the building was raised evenly so that it didn't crack. I suspect that the higher level of integration between modern buildings and their foundations probably means that it's going to be cheaper to just tear down the buildings and rebuild them. My best friend is a structural engineer, so it would be interesting to see what he has to say on the topic. If Miami is anything like Chicago, all the buildings are probably built on piles already, and burying them is one of the most time consuming and expensive parts of the construction process. If you could re-use the piles for a new building you might be able to get away with rebuilding buildings on the cheap. I suspect raising the vast majority of buildings would still be eminently possible though. You see this all of the time in flood-prone areas already. The only difference is that you'd be adding fill up to your new front door.