As viewed from the Pnyx, the Acropolis of Athens is the best known acropolis (high city) in Greece. Although there are many others, the significance of the Acropolis of Athens is such that it is commonly known as The Acropolis without qualification. A flat-topped rock rising 150 m (512 ft) above sea level from the plain of Attica with steep cliffs on three sides, it was also known as Cecropia, after the legendary serpent-man, Kekrops or Cecrops, the first Athenian king.
The first habitation remains date from the Neolithic period. Over the centuries, the "Sacred Rock" of Athens was 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 indicate that the cult of the city's patron goddess was established as early as the Archaic period (650-480 B.C.).
During the Classical period (450-330 B.C.) three important temples were erected on the ruins of earlier ones: the Parthenon, the Erechtheion, and the Temple of Athena 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 were converted into Christian churches, houses of the Franks and later on, of the 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.
Accessible by foot only to the west, where it is linked by a low ridge to the hill of the Areopagus, the Acroplois is formed by a layer of blue-grey limestone, which is very hard but water-permeable. This rests on a layer of schist-sandstone marl, softer than the limestone but water-impermeable, leading to the ready formation of artesian springs, as well as sheltered caves at the hill's feet, which was attracted human habitation on and around the rock.