According to Greek Mythology it was the most sacred of all islands in Ancient Greek culture (Calllimacus 3rd century BC). It was chosen as the birthplace of God Apollo of daylight and his twin sister Artemis of night light by their mother Leto. Their father was Zeus.

Delos, if you would be willing to be the abode of my son Phoebus Apollo and make him a rich temple –; for no other will touch you, as you will find: and I think you will never be rich in oxen and sheep, nor bear vintage nor yet produce plants abundantly. But if you have the temple of far-shooting Apollo, all men will bring you hecatombs and gather here, and incessant savour of rich sacrifice will always arise, and you will feed those who dwell in you from the hand of strangers; for truly your own soil is not rich. — Homeric Hymn to Delian Apollo 51–60

It is estimated that, circa 90 B.C., about 30,000 people lived on this small island, which is no more than a dot on the map of the Mediterranean. The names inscribed on the tombstones in the ancient cemetery provide us with evidence that during the 2nd c. B.C., apart from the island’s majority of Athenian and Roman residents, Delos was populated by folk from most Mediterranean cities: from the Peloponnese and Italy, from mainland regions, Central, Western Greece and Macedonia, Thrace, the Black Sea and Asia Minor, from the Aegean Islands, Cyprus, Crete, and faraway places including Troas, Mysia, Aiolis, Ionia, Lydia, Caria, Lycia, Bithynia, Paflagonia, Pontus, Cappadocia, Pisidia, Pamphilia, Cilicia, Syria, Media, Phoenicia, Palestine, Libya, Arabia and Egypt. Delos was definitely an important and prosperous trading port.

At this time, all these people, in spite of their varied nationalities and different historical and cultural backgrounds, managed to forge a peaceable society. They communicated with each other in spoken and written Greek, the inter-national language of the period, adopted the Greek lifestyle, lived in Greek-style houses and built Greek temples, where they freely worshiped the gods of their homelands. The islanders worked companionably and enjoyed community life, while their children played together, studied at same Gymnasium, and trained in the same Palaestrae.

The excavations, that started in 1872 and are still in progress, have unearthed the Sanctuary and a good part of the cosmopolitan Hellenistic town.