Plans exist, I kid you not. Alison Furuto captions:
The Earthscraper, designed by BNKR Arquitectura, is the Skyscraper’s antagonist in the historic urban landscape of Mexico City where the latter is condemned and the preservation of the built environment is the paramount ambition. It preserves the iconic presence of the city square and the existing hierarchy of the buildings that surround it.
The design is an inverted pyramid with a central void to allow all habitable spaces to enjoy natural lighting and ventilation. To conserve the numerous activities that take place on the city square year round (concerts, political manifestations, open-air exhibitions, cultural gatherings, military parades.), the massive hole will be covered with a glass floor that allows the life of the Earthscraper to blend with everything happening on top.