A flying buttress is a horizontally extending, free standing arch between the wall parts. The bow is so backed up that above a straight - final results - usually covered. Arches are used to support of opposing walls or buildings and can span whole streets. Arches were doing sometimes used as a passageway between the upper floors of the supported houses.
In the Auvergnat Romanesque inner Vierungsbereich is pulled down flying buttress stresses ( Collegiate Church of Notre -Dame du Port, Clermont- Ferrand, Priory Church of Saint-Nectaire (Puy -de- Dôme )), where the Carolingian Church of Germigny -des- Prés (806 ) could have served as a model.
Black alley in Görlitz
Greeks in Vienna