For centuries people have been trying to tame rivers and tides by drilling the subsoil beyond the ground on which we live. These architectural remains, hostile to humans and most animals, form a kind of invisible road system directly under the ground of our cities. By definition, a shelter is a basic architectural structure that provides protection from local environment. Having a place of refuge, safety and retreat is generally regarded as a basic physiological human need, which is the basis for the development of higher human motivations. From this origin Mischa Leinkauf began an intensive exploration of lifeless architectural structures that lie underground. While he stayed in these upside down areas of the city, Leinkauf’s perspective changed from exo- to endogenous. A process that originate from within an organism or a cell. The womb of the city. The work series Endogenous Error Terms captures moments of being inside these left alone architectural spaces in Japan, Mongolia, Russia, Germany, Greece, Austria and Italy. The work consists of an immersive 1-channel video work and an ongoing photo series that brings the audience right into an unseen area of all our busy metropolis.