The idea of the arch as a compression member is presented. The statical work of the arch is illustrated with experiments on photoelastic models. The search for optimal shapes of arches is discussed. A study includes historical development of the arch from the Sumerian times up into the XX century. Examples of arches have been derived from Western Europe, Middle East and Asia; there are also examples of arches in Polish architecture, not well known in the United States. A selection of modern constructions illustrates actual trends in arch applications in contemporary architecture. / M. Arch.