Andros, or Andro (Greek: Άνδρος) is the northernmost island of the Greek Cyclades archipelago, approximately 10 km (6 mi) south east of Euboea, and about 3 km (2 mi) north of Tinos. It is nearly 40 km (25 mi) long, and its greatest breadth is 16 km (10 mi). Its surface is for the most part mountainous, with many fruitful and well-watered valleys. The area is 380 km2 (147 sq mi). The largest towns are Andros (town), Gávrio, Bátsi, and Órmos Korthíou.
The island is famous for its Sariza spring at Apoikia where the water comes out of a lionhead. Palaeopolis, the ancient capital, was built into a steep hillside, and its harbor's breakwater can still be seen underwater.
The island in ancient times contained an Ionian population, perhaps with an admixture of Thracian blood. Though originally dependent on Eretria, by the 7th century BC it had become sufficiently prosperous to send out several colonies, to Chalcidice (Acanthus, Stageira, Argilus, Sane). The ruins of Palaeopolis, the ancient capital, are on the west coast; the town possessed a famous temple, dedicated to Dionysus. In 480 BC, it supplied ships to Xerxes and was subsequently harried by the Greek fleet. Though enrolled in the Delian League it remained disaffected towards Athens, and in 477 had to be coerced by the establishment of a cleruchy on the island nevertheless, in 411 Andros proclaimed its freedom, and in 408 withstood an Athenian attack. As a member of the second Delian League it was again controlled by a garrison and an archon. In the Hellenistic period, Andros was contended for as a frontier-post by the two naval powers of the Aegean Sea, Macedon and Ptolemaic Egypt. In 333, it received a Macedonian garrison from Antipater in 308 it was freed by Ptolemy I of Egypt. In the Chremonidean War (266-263) it passed again to Macedon after a battle fought off its shores. In 200, it was captured by a combined Roman, Pergamene and Rhodian fleet, and remained a possession of Kingdom of Pergamon until the dissolution of that kingdom in 133 BC. Before falling under Turkish rule, Andros was from AD 1207 till 1566 governed by the families Zeno and Sommariva under Venetian protection. After a few centuries, Cyclades joined the rest of Greece in 1821.
On May 10, 1821, Theophilos Kairis, one of the leading intellectuals of the Greek Revolution, declared the War of Independence by raising the Greek flag at the picturesque cliffside church of St George: at this time, a famous heartfelt speech, or "rhetoras", inspired shipowners and merchants to contribute funds to build a Greek Navy to combat the Ottomans.