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 was used as a treasury. For a time, it served as the treasury of the Delian League, which later became the Athenian Empire. In the 5th 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, and it had a minaret built in it. On 26 September 1687, an Ottoman ammunition dump inside the building was ignited by Venetian bombardment. The resulting explosion severely damaged the Parthenon and its sculptures.