with a diameter of 1 m (3.1 ft) at the base and 79 cm (31 inches) at the top. Fortress In 413 BC, during the Peloponnesian War against the Spartans, the Athenians fortified the site with a wall and towers to prevent it from falling into Spartan hands. This would have threatened Athens' seaborne grain supply route from Euboea. Athens' supply situation had become critical since the city's land supply lines had been cut by the Spartan fortification of Dekeleia, to the north of Attica. The Sounion fortress was soon later seized from the Athenians by a force of rebel slaves from the nearby silver mines of Laurium. The Temple of Poseidon was situated in the southeastern corner of the fortress, with the garrison quarters arranged along a main stream on the western slope of the hill. The fortress included a small naval base, with a shipshed for two warships in the northwestern corner (). The fortress was maintained well into the Hellenistic period. Repairs and additions to the fortress were made during the Chremonidean War (266–261 BC). Literary reception The name Capo Colonne (graecicized Kavokolones) is reported from the 17th century, for the reason that unusually, several columns of the temple of Poseidon had remained standing since antiquity. Early modern descriptions in travelogues include those by G. Wheler (1676), J.-D. Le Roy (1754), R. Chandler (1765) and E. Dodwell (1805). Scottish poet William Falconer (1732-1769) was shipwrecked off Cape Colonna, as Sounion was then known, in 1750, an event depicted in the central scene of his The Shipwreck (1762). The inscribed name of George Lord Byron, carved into the base of one of the columns of the Temple of Poseidon, possibly dates from his first visit to Greece, on his Grand Tour of Europe before he acquired fame. Byron spent several months in 1810–11 in Athens, including two documented visits to Sounion. There is, however, no direct evidence that the inscription was made by Byron himself. Byron mentions Sounion in his poem Isles of Greece: Place me on Sunium's marbled steep, Where nothing, save the waves and I, May hear our mutual murmurs sweep... Martin Heidegger visited Sounion during his journey to Greece in 1962, as described in his book Sojourns. He refers to the "gleaming-white ruins of the temple". In the strong sea breeze "these few standing columns were the strings of an invisible lyre, the song of