[notahacker]

The Plattenbau were mostly composed of system built concrete panels and frames assembled into rooms onsite, with only the small bathrooms being delivered to site as complete units.

These appear to be structures composed entirely of stacked full-size room unit completed before site delivery and winched into place; but that technique's been around (especially in the hotel industry) for a good while too, although it's only in the last 20 years people have started to build structures of over 10 storeys that way

Nothing's ever truly new. The Romans used prefabricated elements to speed up fort construction in the first century AD.