[rejfpvav] Building a pyramid from the top down

Build a small pyramid.  Jack it up on stilts.  Build a new bottom layer.  Remove stilts.  Repeat.

One does not have to decide in advance how large the final pyramid will be, and, in particular, how strong a base layer to create in order to be able to support an unknown number of stories above it.  Each new bottom floor needs only to be strong enough to support the existing floors above; no new weight will ever be added.  (Except: stronger winds with greater height, more severe earthquake shaking.)

There remains the formidable-looking problem of lifting a building, especially since buildings are usually securely attached to foundations for a good reason.