Some time ago I read/saw or otherwise absorbed that sky scrapers are hung from the top not supported at the bottom. The logic is that if the outer walls are structural then in the event of a tremor or strong wind the whole structure will shear and cause damage, whereas if it is suspended from a strong central column then it will bend and retain its structure.
I took the opportunity of looking at a couple of skyscraper pulli going up at the east end of Canary Wharf to see if I could spot this. The first is just the lift shaft going up. It looks an immense block of concrete, and already has the floor numbers on.
The second is more developed, and the floor construction seems to be sprouting out of the central lift shaft.
If anyone has more knowledge or has spotted mistakes then please let me know!