Aenus (Greek: Αἶνος), modern Enez in Turkey, was an ancient Greek city on the southeastern coast of Thrace. Formerly called Poltyobria (or Poltymbria), it was located near the mouth of the Hebrus River, not far from the Melas Gulf (modern Gulf of Saros), which is formed by the Thracian Chersonesus to the east. The city was said to be founded (or at least settled) by Aeolian migrants from Lesbos.
Aenus is mentioned by several ancient authors (e.g., Homer, Strabo, Apollodorus, Thucydides), and makes several appearances in Greek mythology. Its mythical and eponymous founder was said to be Aeneus, a son of the god Apollo and father of Cyzicus. Another mythical ruler, named Poltys, son of Poseidon, entertained Heracles when he came to Aenus. On that occasion, Heracles slew Poltys' insolent brother Sarpedon on the beach of Aenus. According to Strabo, Sarpedon is the name of the coastline near Aenus, so both Poltys and Sarpedon would appear to be eponyms.
In the late Middle Ages, Ainos became a domain of the Gattelusi, the Genoese family that ruled much of the northern Aegean while nominally subject to the Byzantine Empire. Three Gattelusi ruled over the town and neighbouring islands, Niccolò Gattilusio, Palamede Gattilusio and Dorino II Gattilusio. In 1456 the town was captured by the Ottoman Sultan Mehmed II.
- Petit, L. Typicon du monastère de la Kosmosotira près d'Aenos (1152. - Izvestija Russkogo arheologicheskogo instituta v Konstantinopole, T. XIII (1908), pp. 17-77