Readers of Arthur C. Clarke’s Fountains of Paradise or 3001 know of a structure he proposed; essentially a giant ring around the earth connecting multiple space elevators together.  Something like this would provide an enormous increase in living space and a save haven for millions in the event of a planetary wide catastrophe.

Paul Lucas discusses this and other megastructures in this very interesting web posting.  People who “think big” enough to be comfortable with the idea of a Space Elevator should also be comfortable with other concepts Mr. Lucas discusses.