Delos was the most important Panhellenic sanctuary, and, according to mythology, the birth-place of Apollo and Artemis.
The first signs of habitation on the island date from the 3rd millenium B.C., and important remains of the Mycenaean period have been uncovered in the area of the sanctuary. In the 7th century B.C. Delos was already a known Ionic centre because of its religious importance as the birth-place of Apollo.
Athenian influence was initiated on the sanctuary with the first purification of Delos by Peisistratos in 540 B.C. but it gradually developed into a proper domination lasting - with short intervals - until the end of the 4th century B.C., when Delos was finally declared free and independent (314 B.C.).
The independence of the island lasted until 166 B.C. when the Romans gave it over to the Athenians.
The second Athenian domination started with the definite expulsion of the Delians to Achaia, in the Peloponnese. The declaration of Delos as an "international" harbour by the Romans led to an influx of foreigners who became a significant element of the island's population. The absence of taxes resulted to the concentration of trade activity on the island and, subsequently, to its economic prosperity.
The close relations of Delos with Rome, though, was the main reason for its decline. During Mithridates' wars againts the Romans, Delos suffered severe damage in the raids of 88 B.C. and 69 B.C. Since then, the island's prosperity gradually came to an end. In the 2nd and 3rd centuries A.D. only a small settlement existed on Delos and, as Christianity had gradually replaced the ancient religion, the island finally lost its importance.
Delos was a sacred place with splendid buildings and sanctuaries and as such, it was never forgotten; many references are preserved by travellers who visited the island in the last centuries. Numerous pieces of sculpture were transferred to Museums of Greece and abroad, while marbles from the ancient buildings were used as building material by the inhabitants of the nearby islands.
Large-scale restoration work has been undertaken by the French School of Archaeology mainly in the sector of the private houses, but in the recent years, the 21st Ephorate of Prehistoric and Classical Antiquities has also carried out similar work. Several columns have been rebuilt and ancient houses have been roofed in order to protect the mosaic floors (House of the Trident, House of the Masks, House of Hermes). In 1990 Delos was included in the World's Cultural Heritage, protected by the UNESCO.
Excavations on Delos started in 1873 by the French School of Archaeology at Athens. Between 1904 and 1914, under the direction of M. Holleaux and thanks to the donation of Duke de Loubat, the most significant sections of the ancient site were uncovered.
Intensive excavations were conducted in the years 1958-1975. The excavations are still carried out by the French School of Archaeology, but the religious, political and commercial centre of the island has already been revealed along with many private houses. Restricted excavations were also conducted by Greek archaeologists at the beginning of the century.