Shimizu Mega-City Pyramid
The Shimizu TRY 2004 Mega-City Pyramid is a proposed Shimizu Corporation project for the construction of a massive self-sustaining arcology-pyramid over Tokyo Bay in Japan that would have businesses, parks, and other services contained within the building. The structure would house 1,000,000 people.
Source: Wikipedia — Shimizu Mega-City Pyramid (CC BY-SA 4.0)