The Parthenon is the fourth temple to stand on this site. Of the first and second, little is known. The second temple, called by some the Hektompedon, dates to the 6th century BC. The third temple was the uncompleted "pre-Parthenon" temple, whose construction was halted by the sack of the Persians in 480 BC. The fourth version of the Parthenon was initiated by Pericles and its construction began in 447 BC and was finished by 435 BC. This form of the temple remained more or less intact for 2000 years. In the 6th century, Justinian turned the Parthenon into a Christian church, dedicated to the Virgin Mother of God. Doorways, frescoes, and structural embellishments to support the functioning of a Christian church were added. In 1687, a mortar shell struck the Parthenon, which at that time was being used as a powder magazine by the Turks. The cella, its frieze, fourteen columns, and much entablature was badly damaged. Once Morosini (whose troops had fired the shell) gained access to the Acropolis, he ordered the west pediment to be removed as booty. The attempt caused the entire chariot group of Athena to fall to its ruin. During the 18th century, a mosque was built in the ruins of the Parthenon. Early antiquarians such as Elgin also began to cart away large portions of the temple's sculpture. Restoration was finally begun in the 19th and 20th centuries.