Kos or Cos (Greek: Κως; Turkish: İstanköy; Italian: Coo; formerly Stanchio in English) is a Greek island in the south Sporades group of the Dodecanese, next to the Gulf of Gökova/Cos. It measures 40 km by 8 km, and is only 4 km from the coast of Bodrum, Turkey and the ancient region of Caria. The island has both fertile plains and infertile highlands with a population of 30,947. It is comprised of three municipalities: Kos, the administrative center and largest town (pop. 17,890), Dikaio, and Irakleides.
The island was originally colonised by the Carians. A contingent from Kos participated in the War of Troy The Dorianss invaded it in the 11th century BC, establishing a Dorian colony with a large contingent of settlers from Epidaurus who took with them their Asclepius cult and made their new home famous for its sanatoria. The other chief sources of the island's wealth lay in its wines, and in later days, in its silk manufacture.
Its early history as part of the religious-political amphictyony that included Lindos, Kamiros, Ialysos, Cnidus, and Halicarnassus, is obscure. At the end of the 6th century Kos fell under Achaemenid domination, but rebelled after the Greek victory at Cape Mykale in 479. During the Greco-Persian Wars, when it expelled the Persians twice, it was ruled by tyrants, but as a rule it seems to have been under an oligarchic government. In the 5th century it joined the Delian League, and after the revolt of Rhodes served as the chief Athenian station in the south-eastern Aegean (411-407). In 366 BC, a democracy was instituted. After helping to weaken Athenian power, in the Social War (357-355 BC), it fell for a few years to the king Mausolus of Caria. In 366 BC, the capital was transferred from Astypalaia to the new-built town of Kos, laid out in a Hippodamian grid plan.
In the Hellenistic age Kos attained the zenith of its prosperity. Its alliance was valued by the kings of Egypt, who used it as an outpost for their navy to watch the Aegean. As a seat of learning it rose to be a kind of provincial branch of the museum of Alexandria, and became a favorite resort for the education of the princes of the Ptolemaic dynasty; among its most famous sons were the physician Hippocrates, the painter Apelles, the poets Philitas and, perhaps, Theocritus.
Kos was also known as Meropis and Nymphæa. Diodorus Siculus (xv. 76) and Strabo (xiv. 657) describe it as a well-fortified port. Its position gave it a high importance in Ægean trade; while the island itself was rich in wines of considerable fame (Pliny, xxxv. 46). Under Alexander III of Macedon and the Egyptian Ptolemies (from 336 B.C.) the town developed into one of the great centers in the Ægean; Josephus ("Ant." xiv. 7, § 2) quotes Strabo to the effect that Mithridates was sent to Kos to fetch the gold deposited there by the queen Cleopatra of Egypt. Herod is said to have provided an annual stipend for the benefit of prize-winners in the athletic games (Josephus, "B. J." i. 21, § 11), and a statue was erected there to his son Herod the Tetrarch ("C. I. G." 2502 ).
Except for occasional incursions by corsairs and some severe earthquakes, the island has rarely had its peace disturbed. Following the lead of its great neighbour, Rhodes, Kos generally displayed a friendly attitude towards the Romans; in 53 AD it was made a free city. The island was later conquered by the Venetians, who then sold it to the Knights Hospitaller of Rhodes (the Knights of St John) in 1315. Two hundred years later the Knights faced the threat of a Turkish invasion and abandoned the island to the Ottoman Empire in 1523. The Ottomans ruled Kos for 400 years until it was transferred to Italy in 1912. In World War II, the island was taken over by Germany until 1945, when it became a protectorate of the United Kingdom, who ceded it to Greece in 1947.
The island is part of a chain of mountains from which it became separated after earthquakes and subsidence that occurred in ancient times. These mountains include Kalymnos and Kappari which are separated by an underwater chasm c. 70 m (40 fathoms deep), as well as the volcano of Nisyros and the surrounding islands.
There are a wide variety of rocks in Kos which is related to its geographical formation. Prominent among these are the Quaternary layers in which the fossil remains of mammals such as horses, hippopotami and elephants have been found. The fossilised molar of an elephant of gigantic proportions was presented to the Paleontology Museum of the University of Athens.
The shores of Kos Island are washed by the waters of the Aegean Sea. Its coastline is 112 km long and is caressed by long immaculate beaches, leading to its main industry being tourism. Farming is the principal occupation of many of the island's inhabitants, with their main crops being grapes, almonds, figs, olives, and tomatoes, along with wheat and corn. Cos lettuce may be grown here, but the name is unrelated.
The main port and population centre on the island, also called Kos, is also the tourist and cultural centre, with whitewashed buildings including many hotels, restaurants and a small number of nightclubs forming the famous Kos town "barstreet". The town has a 14th century fortress at the entrance to its harbour, erected in 1315 by The Knights of Saint John of Rhodes.
The ancient physician Hippocrates is thought to have been born on Kos, and in the center of the town is the Plane Tree of Hippocrates, a dream temple where the physician is traditionally supposed to have taught. The limbs of the now elderly tree are supported by scaffolding. The small city is also home to the International Hippocratic Institute and the Hippocratic Museum dedicated to him. Near the Institute are the ruins of Asklepieion, where Herodicus taught Hippocrates medicine. Kardamena is a popular resort for young British holidaymakers and has a large number of bars and nightclubs.
The main religion practiced is Greek Orthodoxy. Kos has one of the four cathedrals in the entire Dodecanese. There is also a Roman Catholic Church on the island as well as a Mosque catering to the Muslim community of Kos. The Synagogue is no longer used for religious ceremonies as the Jewish community of Kos was practically wiped out by the Nazis in World War II. It has, however, been restored and is maintained with all religious symbols intact and is now used by the Municipality of Kos for various events, mainly cultural.