Quantifying the distance to the Bussière model: mono-centrism against "acentrism" This article aims at quantifying the extent to which an urban region is dissimilar to the monocentric model formalized by Bussière. Extremes forms of non-monocentricity - such as a uniform pattern - will be called "acentric". An index of acentricity is thus proposed, and compared with classical urban structure indicators (Hoover index, Moran index, rank-size slope), for theoretical as well as empirical patterns - twenty-five cities in Europe have been looked at. We emphasize the necessity to a multi-dimensional approach of urban structure. Within this framework, quantifying the dissimilarity to the monocentric model may be useful.