Architecture of density
In Japan most of the people doesn’t live in condominiums, they prefer single-houses. Even though, there are some areas where there are lots of buildings that seem to be designed with the only purpose of keeping the maximum number of families without using too much space. The worst city in the world creating horrible huge buildings is Hong Kong, where the rich zone has incredible beautiful skycrapers but the poor suburbs are full of “architecture of density” (Click this link, the photos are impressive).
I took these photos at east-Tokyo: