The French mail carrier who spent 33 years building Le Palais idéal or the "Ideal Palace"

An influential series of prints started in 1745. 16 imaginary subterranean prisons with winding stairs strange architecture.

In the 1960s architect Ron Herron (1930 - 1994) designed collages of his concept of Walking Cities.

Architect Oscar Newman’s tongue in cheek 'Plan for an underground nuclear shelter' (1969)