Acropolis, the common Greek name for all fortified citadels. In ancient Greece the most notable of these citadels were those at Corinth, Thebes, Argos, and Messene; but the term is especially used of the rocky eminence that crowns the city of Athens. This is a square, craggy mass, with steep sides, about 150 feet high; the flat summit has a length of 1,000 feet and a breadth of 500. The view from this eminence is naturally very commanding, and now affords an admirable opportunity to the visitor of realising the relative positions of the historical landmarks of Athens. After the Persian war it was uninhabited, and dedicated solely to the worship of Athena. A splendid flight of marble steps led up from the Agora to the Propylaea, or porch of the enclosure. This noble structure of pure Pentelic marble consisted of a grand central entrance decorated with massive Doric columns and two side galleries, that to the left being the Pinakotheka, or museum of pictures. The temple of Nike Apteros faced the W. front. On passing through the gateway the Parthenon immediately met the eye. It also was of Pentelic marble and in the Doric style. The building, 228 feet in length, 101 feet in breadth, and 66 feet high to the top of the pediment, displayed 50 majestic columns, enclosing a cella that contained two chambers of unequal size. The metopes within and the friezes without were sculptured in high and low relief respectively, and the whole building was full of sculptures and statues, all executed under the direction of Phidias, who himself carved the marvellous colossal statue of Athena. This magnificent figure, 40 feet in height, was of ivory where the flesh was represented, and the drapery was of solid gold. It was probably tinted. A still larger effigy of the virgin goddess in bronze stood in front of the Parthenon, and towered above it so as to serve as a landmark to ships at sea. Another glory of this sacred spot was the Erechtheum, where Poseidon was worshipped. Its date is later than that of the Parthenon, and its style Ionic. Here sprang up the primeval olive tree at the bidding of Athena, and here could be seen the imprint of Poseidon's trident on the rock. In a hollow beneath the Acropolis lay the cave of Pan.