The Parthenon is a former temple on the Athenian Acropolis, Greece, dedicated to the goddess Athena, whom the people of Athens considered their patron. Construction began in 447 BC when the Athenian Empire was at the peak of its power. It was completed in 438 BC, although decoration of the building continued until 432 BC. It is the most important surviving building of Classical Greece, generally considered the zenith of the Doric order. Its decorative sculptures are considered some of the high points of Greek art. The Parthenon is regarded as an enduring symbol of Ancient Greece, Athenian democracy and Western civilization, and one of the world's greatest cultural monuments. To the Athenians who built it, the Parthenon and other Periclean monuments of the Acropolis were seen fundamentally as a celebration of Hellenic victory over the Persian invaders and as a thanksgiving to the gods for that victory. The Parthenon itself replaced an older temple of Athena, which historians call the Pre-Parthenon or Older Parthenon, that was destroyed in the Persian invasion of 480 BC. Like most Greek temples, the Parthenon served a practical purpose as the city treasury. For a time, it served as the treasury of the Delian League, which later became the Athenian Empire. In the final decade of the 6th century AD, the Parthenon was converted into a Christian church dedicated to the Virgin Mary. After the Ottoman conquest, it was turned into a mosque in the early 1460s. On 26 September 1687, an Ottoman ammunition dump inside the building was ignited by Venetian bombardment during a siege of the Acropolis. The resulting explosion severely damaged the Parthenon and its sculptures. From 1800 to 1803, Thomas Bruce, 7th Earl of Elgin removed some of the surviving sculptures, now known as the Elgin Marbles, with the alleged permission of the Turks of the Ottoman Empire. Since 1975 numerous large-scale restoration projects have been undertaken; the latest is expected to finish in 2020.