A pilaster is an architectural feature, originating in ancient Roman architecture, which consists of a flat rectangular strip attached to the wall, sometimes with a fluted surface or more ornate decoration. Pilasters usually stand on a base and are topped by a capital, as in those on either side of the entrance to the Virgin's room in Crivelli's 'The Annunciation, with Saint Emidius'. The name is also given to a similar structure on the outer sides of an altarpiece frame. In some cases the pilasters have figures of standing saints, as in Giovanni del Ponte's 'Ascension of Saint John the Evangelist' (19th-century frame).