On the under surface of the main archivolt are fourteen most beautiful carvings, representing the chief guilds and crafts of Venice. To the L.,[86] at the bottom, is a seated figure with finger on lip, said by Ruskin to represent the rest of old age; by tradition it is the portrait of the architect of the building, of whom the following story is told. When Doge Pietro Orseolo determined to restore the church after the fire of 976, a queer, unknown man, lame in both legs, offered to make St Mark’s the most beautiful structure ever erected, if, on completion, his statue were placed in a conspicuous part of the building. His terms were accepted, but after the work had progressed some time, the stranger incautiously let fall a remark to the effect that the church would have been much more magnificent if certain difficulties had not intervened. Word was sent to the Doge, and the statue was set in its present obscure position. [Illustration: S. MARCO--DETAIL OF MAIN DOOR] On either side of the main portal are two doorways, spanned by richly decorated Byzantine arches; that to the L., has the figure of Christ in the keystone and two prophets with scrolls in the spandrils; that to the R. has the keystone defaced; in the spandrils to the R. and L. are the archangels Michael and Gabriel. The lateral doorway to the L. has in the lunette a winged figure on horseback and symbols of the Evangelists; on the lintel are some fine Gothic reliefs. The pierced screen-work in the lunette windows should be noted, for in olden times the whole of the window spaces in the domes were thus treated. The corresponding doorway to the R. has in the spandrils, carvings of two archangels, and on the keystone the Virgin and Child. The beautiful lily capitals are at either end of the façade, and support the arches that span the N. and S. porticos. The late fifteenth-century Gothic additions consist of pinnacles and gables of no structural value. They are seen in Gentile Bellini’s picture,[87] dated 1496, of the Procession in St Mark’s Square, but are absent in the extant thirteenth-century mosaic on the façade.