The earliest known form of Greek chair dates back to six or seven centuries BCE. On the frieze of the Parthenon, Zeus occupies a square seat with a bar-back and thick turned legs; it is ornamented with winged sphinxes and the feet of beasts. The characteristic Roman chairs were of marble, also adorned with sphinxes. The curule chair was originally very similar in form to the modern folding chair, but eventually received a good deal of ornament. The most famous of the very few chairs which have come down from a remote antiquity is the reputed Chair of Saint Peter in St Peter's Basilica at Rome. The wooden portions are much decayed, but it would appear to be Byzantine work of the 6th century, and to be really an ancient sedia gestatoria. It has ivory carvings representing the labours of Hercules. A few pieces of an earlier oaken chair have been let in; the existing one, Gregorovius says, is of acacia wood. The legend that this was the curile chair of the senator Pudens is necessarily apocryphal. It is not, as is popularly supposed, enclosed in Gian Lorenzo Bernini's bronze chair, but is kept under triple lock and exhibited only once in a century. Byzantium, like Greece and Rome, affected the curule form of chair, and in addition to lions’ heads and winged figures of Victory (orNike) and dolphin-shaped arms used also the lyre-back which has been made familiar by the pseudo-classical revival of the end of the 18th century.