I think they are referring to post-war social housing common in Europe. The concrete exteriors were meant to convey stability in a society wrought with precarity. Those raised in these buildings generally express this exact sense of appreciation. An architecture nerd, I find these buildings simply marvelous. The style is termed ‘Brutalist’ architecture.

EDIT: I didn’t see their link before but, after following it, I guess it’s not what they meant.

https://en.m.wikipedia.org/wiki/Soviet_architecture