The Critical Mass: The new headquarters of the Federal Intelligence Service located in downtown Berlin—the largest building project in the Federal Republic of Germany since 1945—on a ten-hectare piece of property.

Based on the master plan by Jan Kleihues, a concept was implemented for the overall site and the functionally very complex main building that was to do justice both to the location as well as the requirements of the federal law enforcement agency. In its differentiated execution of a self-confident architectural language, it represents a prominent building block that lends the site its constitutive identity.

This monograph provides exclusive insights into a building that is otherwise closed to the public. It shows how the challenging multilayered construction project was solved both internally and externally and affords a look at unexpected details. Selected text contributions throw light on its history and the competition as well as the design and its realization.