Andros (Ancient Greek: Ἄνδρος) was the chief city of, and a polis (city-state) on, the island of Andros in the Aegean Sea. The city was named after the island, which, according to tradition, derived its name either from Andreus, a general of Rhadamanthus or from the seer Andrus. It was colonized by Ionians, and early attained so much importance as to send colonies to Acanthus and Stageira in Chalcidice about 654 BCE. The Andrians were compelled to join the fleet of Xerxes I in his invasion of Greece, in 480 BCE; in consequence of which Themistocles attempted to levy a large sum of money from the people, and upon their refusing to pay it, laid siege to their city, but was unable to take the place.
The site was situated nearly in the middle of the western coast of the island, at the foot of a lofty mountain. Its citadel strongly fortified by nature is mentioned by Livy. It had no harbour of its own, but it used one in the neighbourhood, called Gaurion (Γαύριον) by Xenophon, and Gaureleon by Livy, and which still bears the ancient name of Gavrio.