The Acropolis hill, the so-called Sacred Rock of Athens, is the most important site of the city. During Perikles' Golden Age, ancient Greek civilization was represented in an ideal way on the hill and some of the architectural masterpieces of the period were erected on its ground. The first habitation remains on the Acropolis date from the Neolithic period. Over the centuries, the rocky hill was continuously used either as a cult place or as a residential area or both. The inscriptions on the numerous and precious offerings to the sanctuary of Athena (marble korai, bronze and clay statuettes and vases) indicate that the cult of the city's patron goddess was established as early as the Archaic period (650-480 BC).
  During the Classical period (450-330 BC) three important temples were erected on the ruins of earlier ones: the Parthenon, the Erechtheion and the Temple of Nike, dedicated to Athena Parthenos, Athena Polias and Athena-Apteros Nike respectively. The Propylaea, the monumental entrance to the sacred area was also constructed in the same period.
  The monuments on the Acropolis reflect the successive phases of the city's history. Some of them were converted into Christian churches, houses of the Franks and, later on, of the Ottoman Turks. After the liberation of Athens from the Turks, the protection, restoration and conservation of the monuments was one of the first tasks of the newly-founded Greek state. This major effort is continued until today, with the large-scale restoration and supporting of the monuments, which started in the 1970's and is still in progress.
  The first excavations on the hill were conducted between 1835 and 1837. More systematic work was carried out in 1885-1890 by Panagiotis Kavvadias.
  The most important monuments on the Acropolis are:
The Parthenon is the most important and characteristic monument of the ancient Greek civilization and still remains its symbol worldwide. It was dedicated to Athena Parthenos, the patron goddess of Athens. The temple was built between 447 and 438 BC and its sculptural decoration was completed in 432 BC. The construction of the monument was initiated by Perikles, the supervisor of the whole work was Pheidias, the famous Athenian sculptor, while Iktinos and Kallikrates were the architects. The temple is built in the Doric order and almost exclusively of Pentelic marble. It is peripteral, with eight columns on each of the narrow sides and seventeen columns on each of the long ones. The central part of the temple, called the cella, sheltered the famous chryselephantine cult statue of Athena, made by Pheidias.
  The sculptural decoration of the Parthenon is a unique combination of the Doric metopes and triglyphs on the entablature, and the Ionic frieze on the walls of the cella. The metopes depict the Gigantomachy on the east side, the Amazonomachy on the west, the Centauromachy on the south, and scenes from the Trojan War on the north.
  The relief frieze depicts the Procession of the Panathenaea, the most formal religious festival of ancient Athens. The scene runs along all the four sides of the building and includes the figures of gods, animals and of some 360 humans.
  The two pediments of the temple are decorated with mythological scenes: the east pediment, above the building's main entrance, depicts the birth of Athena, while the west represents the fight between Athena and Poseidon over Athens. The Parthenon retained its religious character in the following centuries and was converted into a Byzantine church, a Latin church and a mosque.
  The Turks used the Parthenon as a powder magazine when the Venetians, under Admiral Morosini, sieged the Acropolis in 1687. One of the Venetian bombs fell on the Parthenon and caused a tremendous explosion that destroyed a great part of the monument which had been preserved in a good condition until then.
  The disaster was completed in the beginning of the 19th century, when the British ambassador in Constantinople Lord Elgin stole the greatest part of the sculptural decoration of the monument (frieze, metopes, pediments), transferred them to England and sold them to the British Museum, where they are still exhibited, being one of the most significant collections of the museum.
The Erechtheion was built in ca. 420 BC in the Ionic order. It has a prostasis on the east side, a monumental propylon on the north, and the famous porch of the Caryatids on the south. The main temple was divided into two sections, dedicated to the worship of the two principal gods of Attica, Athena and Poseidon-Erechtheus. A relief frieze, bearing a representation possibly of the birth of Erechtheus, decorated the exterior of the building.
The Temple of Athena Nike was constructed in ca. 420 BC by the architect Kallikrates. It is built in the Ionic order, and it is amphiprostyle with a row of four columns in front of each of its narrow sides. The relief frieze on the upper section of the walls depicts the conference of gods on the east side, and scenes from battles on the other three. A marble parapet decorated with the relief representation of Nikae (Victories), protected the edge of the Bastion on which the temple was erected.
The Propylaea. The monumental gateway of the Acropolis was designed by the architect Mnesikles and constructed in 437-432 BC. It comprises a central building and two lateral wings. The colonnades along the west and east sides had a row of Doric columns while two rows of Ionic columns divided the central corridor into three parts. The walls of the north wing were decorated with painted panels or wall paintings and that is why it was called the Pinakotheke (gallery). The ceiling of the Propylaea had coffers with painted decoration and a perforated sima around the roof.

Links
• http://odysseus.culture.gr/h/3/eh351.jsp?obj_id=2384
• http://whc.unesco.org/en/list/404
• http://www.acropolisofathens.gr