The Erechtheion or Erechtheum is an ancient Greek temple on the north side of the Acropolis of Athens in Greece which was dedicated to both Athena and Poseidon. The temple as seen today was built between 421 and 406 BC. Its architect may have been Mnesicles, and it derived its name from a shrine dedicated to the legendary Greek hero Erichthonius. The sculptor and mason of the structure was Phidias, who was employed by Pericles to build both the Erechtheum and the Parthenon. Some have suggested that it may have been built in honor of the legendary king Erechtheus, who is said to have been buried nearby. Erechtheus was mentioned in Homer's Iliad as a great king and ruler of Athens during the Archaic Period, and Erechtheus and the hero Erichthonius were often syncretized. It is believed to have been a replacement for the Peisistratid temple of Athena Polias destroyed by the Persians in 480 BC. The need to preserve multiple adjacent sacred precincts likely explains the complex design. The main structure consists of up to four compartments, the largest being the east cella, with an Ionic portico on its east end. Other current thinking would have the entire interior at the lower level and the East porch used for access to the great altar of Athena Polias via a balcony and stair and also as a public viewing platform. The entire temple is on a slope, so the west and north sides are about 3 m (9 ft) lower than the south and east sides. It was built entirely of marble from Mount Pentelikon, with friezes of black limestone from Eleusis which bore sculptures executed in relief in white marble. It had elaborately carved doorways and windows, and its columns were ornately decorated (far more so than is visible today); they were painted, gilded and highlighted with gilt bronze and multi-colored inset glass beads. The building is known for early examples of egg-and-dart, and guilloche ornamental moldings. The Theory of Mouldings, p22, Charles Howard Walker (1926), has detailed drawings of some of the decorations.