City in one building, all the shops and apartments under one roof to minimize heating & cooling, transportation, energy and material cost.
Not a really big one, but the Shape Of Things To Come, perhaps.
Impressive. A little scary.
Read "Oath Of Fealty" by Niven & Pournelle.
A mile high & wide cube built in the middle of LA. ( on the site of a burned out neighborhood after a major riot ) Get's into the possible cultural aspects. Good read.
Modular construction, nothing new but seems to be adapted well to green tech. Three floors per day is really only an assembly time and does not reflect the massive amount of design and pre-assembly work as well as site prep. Still cool, though.