According to mythology, the name Delos was conceived as the island initially was a piece of land floating underwater (which is why the ancient Hellenes called it adelon, i.e. unseen). Later, the god Poseidon working on behalf of Zeus, he brought it on the surface of the sea so that godess Litó would be able to give birth to Apollo and Artemis (Diana), children of Zeus. And it was like that the island, from adelon (unseen) became delon (visible, obvious).
The ancient Hellenes thought of the island as sacred, a place of worship to god Apollo and goddess Ártemis (Diana). Which was why people from all over the world could come here freely, even when at war with each other (and enjoy a break from fighting). The rest of the islands in the central Aegean were named Cyclades, because they lie in a circle around the sacred island of Delos (in Greek, circle is cyclos).
The first inhabitants of Delos date from 3000 BC. (probably members of the Cycladic civilization). It is not known when the island started to be a centre of worship, maybe around 2000 BC. The Ionians (Íones), when they settled on the island around 1000 BC., made Delos a commercial station and introduced “Delia”, yearly celebrations which involved athletic and musical contests.
Later, in the 6th century BC. during the Hellenic – Persian war, the Persians never attacked Delos, to show respect to the sacred island. At the Athenian Hegemony (6th – 4th century BC.), Delos financial and military power declined, as the Athenians absorbed them, and different civilisations started to inhabit the island, all of them leaving something sacred and valuable behind. In a way, Delos became a large and rich museum, for a very long time.
From the 2nd until the 6th century AD, the island remains uninhabited. In the 14th century AD, part of the knights of the Order of St. John, Málta branch, settles on the island but loose it 2 centuries later to the Turks. However, the Turks did not keep Delos in their possession for long, in the 17th century pirates occupy it and use it as a military base of operations. Delos was freed during the Hellenic revolution of 1821.
There is a remarkable museum in Delos, both outdoors and indoors, with ruins and relics from several times and several civilisations. This museum would be infinitely richer, if the looters, plunderers and antique traffickers did not strip the archaeological areas systematically for more than 3 centuries. The stolen items are today in museums all over the world and in private collections.