Limnos or Lemnos is an island in the northern part of the Aegean Sea. It is part of the Greek prefecture of Lesbos and has a considerable area, about 438 km² (150 sq.mi). A great part is mountainous, but some very fertile valleys exist. The chief towns are Myrina, on the western coast, and Moudros on the eastern shore of a large bay in the middle of the island. Myrina (aka Kastro) possesses an excellent harbour, and is the seat of all the trade carried on with the island. The hillsides afford pasture for sheep. A few mulberry and fruit trees grow, but no olives. Muscat grapes are grown widely, and are used to produce an unusual table wine that is dry yet has a strong Muscat flavor.

For ancient Greeks, the island was sacred to Hephaestus, god of technology, who— as he tells himself in Iliad I.590ff— fell on Lemnos when his father Zeus hurled him headlong out of Olympus. There, he was cared for by the Sinties, according to Iliad or by Thetis (Apollodorus, Bibliotheke I:3.5), and there with a Thracian nymph Cabiro (a daughter of Proteus) he fathered a tribe called the Cabiroides. Sacred rites dedicated to them were performed in the island.

Hephaestus' forge, which was located on Lemnos, as well as the name Aethaleia, sometimes applied to it, points to its volcanic character. It is said that fire occasionally blazed forth from Mosychlos, one of its mountains. The ancient geographer Pausanias relates that a small island called Chryse, off the Lemnian coast, was swallowed up by the sea. All volcanic action is now extinct.

The name of "Lemnos" is said by Hecataeus to have been a title of Cybele among the Thracians, and the earliest inhabitants are said to have been a Thracian tribe, whom the Greeks called Sintians, "the robbers".