The classical Propylaea replaced a series of earlier gateways. The Propylaea was designed by the architect Mnesikles, who combined elements of the Doric and Ionic order to produce a building that impresses visitors with its elaborate design and the colonnades. The structure has five gates (only the central gate is used today). The northern wing was known as the Pinacotheca (picture gallery) and contained paintings. The spacious room also served as a banquet hall or rest area for visitors. The statue of Hermes Propylaios, patron god of gateways, stood here. A similar building was designed for the southern wing, but the presence of the Temple of Athena Nike forced the architect to change his plans. The Propylaea was never completed, and lifting bosses remain on numerous blocks. Some ancient sources claim that the total cost of the building was 2012 talents, an excessive amount that explains the inability of Athens to finish the project at the time of the Peloponnesian War with Sparta. During the Byzantine period, the Propylaea became a church and residence of the local bishop. In the 13th century, it served as the palace of Athens’ Frankish rulers, who reinforced the fortification with a tall tower next to the Propylaea. The tower was known as Koulas. The Ottomans turned the Propylaea into a powder magazine. Archaeological excavations began only after Greece’s liberation.