its north side, consisting of steep, narrow flights of steps cut in the rock. Homer is assumed to refer to this fortification when he mentions the "strong-built House of Erechtheus" (Odyssey 7.81). At some time before the 13th century BC, an earthquake caused a fissure near the northeastern edge of the Acropolis. This fissure extended some 35 meters to a bed of soft marl in which a well was dug. An elaborate set of stairs was built and the well served as an invaluable, protected source of drinking water during times of siege for some portion of the Mycenaean period. Archaic Acropolis Not much is known about the architectural appearance of the Acropolis until the Archaic era. During the 7th and the 6th centuries BC, the site was controlled by Kylon during the failed Kylonian revolt, and twice by Peisistratos; each of these were attempts directed at seizing political power by coups d'état. Apart from the Hekatompedon mentioned later, Peisistratos also built an entry gate or propylaea. Nevertheless, it seems that a nine-gate wall, the Enneapylon, had been built around the acropolis hill and incorporating the biggest water spring, the Clepsydra, at the northwestern foot. A temple to Athena Polias, the tutelary deity of the city, was erected between 570 and 550 BC. This Doric limestone building, from which many relics survive, is referred to as the Hekatompedon (Greek for "hundred–footed"), Ur-Parthenon (German for "original Parthenon" or "primitive Parthenon"), H–Architecture or Bluebeard temple, after the pedimental three-bodied man-serpent sculpture, whose beards were painted dark blue. Whether this temple replaced an older one, or just a sacred precinct or altar, is not known. Probably, the Hekatompedon was built where the Parthenon now stands. Between 529 and 520 BC yet another temple was built by the Pisistratids, the Old Temple of Athena, usually referred to as the Arkhaios Neōs (ἀρχαῖος νεώς, "ancient temple"). This temple of Athena Polias was built upon the Dörpfeld foundations, between the Erechtheion and the still-standing Parthenon. Arkhaios Neōs was destroyed as part of the Achaemenid destruction of Athens during the Second Persian invasion of Greece during 480–479 BC; however, the temple was probably reconstructed during 454 BC, since the treasury of the Delian League was transferred in its opisthodomos. The temple may have been burnt down during 406/405 BC as Xenophon mentions that the old temple of Athena was set afire. Pausanias does not mention it in