Abstract The ultimate failure load of stone arch bridges is calculated in this paper. The finite element model consists of contact interfaces which simulate potential cracks. A parametric investigation demonstrates the influence of the geometry on the mechanical behavior. A reduction of the rise of the arch (below the initial, real geometry) generally causes an increase of the limit load, until a shallow, flat arch. The results are in agreement with the findings of Heyman. Further reduction of the rise leads to a reduction of the limit load. Furthermore, deep arches fail following the four hinges collapse mechanism, while compressive failure arises in shallow arches. Finally, for settlement of the supports, in accordance with Heyman’s statements, three hinges are developed before collapse of the arch.