Dr. Werff Rönne, the protagonist of Gottfried Benn’s novella cycle Gehirne (1916), is a sort of solitary walker in occupied Brussels during World War I. Described by Helmut Lethen as the «eye of the hurricane », Brussels is hardly mentioned in Benn’s prose and the metropolitan dimension of the setting seems to be marginalized as well. Rönne is from the beginning of the cycle intellectually bankrupt, which prevents him from being a “blasé” à la Simmel, while Brussels is rather the stage of a «mise-en scene of the protagonist’s psychic state» (Huyssen). Focussing on the intersections between science, philosophy and poetics in some of Benn’s early works (Gespräch, Unter der Großhirnrinde) thematically connected to Rönne’s development, this paper shows how the delimited urban space in Gehirne is only the first step towards the aesthetic experience of the dissolution of the limits (Entgrenzung) in the project of a ‘new syntax’.