25 years ago working summer construction projects doing foundations in Siberia we were explained what depth to reach and why (permafrost etc.), and in particular we were taken on a short sightseeing tour of couple of buildings for which it wasn't done properly - the screwed geometry of those buildings one could see with naked eye from distance. I guess that tower in SF will be serving similar educational purpose for decades to come :)
In my hometown there is a building that was built in 1529 and leans more than the tower of pisa. It was intended to be taller than our rival cities tower, but it already started sagging during construction. To counteract the sagging the builders actually made kinks in the construction so next layers would be level again, but obviously this didn't help. They never got further than the base of the tower, which still stands and is a fun place to visit.
