For example, the antae of pronaos and opisthodomos are shortened so as to form simple pillars. Instead of longer antae, there are prostyle colonnades inside the peristasis on the front and back, reflecting Ionic habits. The execution of the naos, with a western room containing four columns, is also exceptional. The Parthenon's Archaic predecessor already contained such a room. All measurements in the Parthenon are determined by the proportion 4:9. It determines column width to column distance, width to length of the stylobate, and of the naos without antae. The temple's width to height up to the geison is determined by the reverse proportion 9:4, the same proportion squared, 81:16, determines temple length to height. All of this mathematical rigour is relaxed and loosened by the optical refinements mentioned above, which affect the whole building, from layer to layer, and element to element. 92 sculpted metopes decorate its triglyph frieze: centauromachy, amazonomachy and gigantomachy are its themes. The external walls of the naos are crowned with a figural frieze surrounding the entire naos and depicting the Panathenaic procession as well as the Assembly of the Gods. Large format figures decorate the pediments on the narrow sides. This conjunction of strict principles and elaborate refinements makes the Parthenon the paradigmatic Classical temple. The Temple of Hephaistos at Athens, erected shortly after the Parthenon, uses the same aesthetic and proportional principles, without adhering as closely to the 4:9 proportion.