Antandrus or Antandros was an ancient Greek city on the north side of the Gulf of Adramyttium in the Troad region of Anatolia. Its surrounding territory was known in Greek as Ἀντανδρία (Antandria), and included the towns of Aspaneus on the coast and Astyra to the east. It has been located on Devren hill between the modern village of Avcılar and the town of Altınoluk in the Edremit district of Balıkesir Province, Turkey.

Balıkesir Province is a province and metropolitan municipality in northwestern Turkey with coastlines on both the Sea of Marmara and the Aegean. Its area is 14,583 km2, and its population is 1,257,590 (2022). Its adjacent provinces are Çanakkale to the west, İzmir to the southwest, Manisa to the south, Kütahya to the southeast, and Bursa to the east. The provincial capital is Balıkesir. Most of the province lies in the Marmara Region except the southern parts of Bigadiç Edremit, Kepsut, İvrindi, Savaştepe and Sındırgı districts and ones of Ayvalık, Burhaniye, Dursunbey, Gömeç and Havran, that bound the Aegean Region. Kaz Dağı, known also as Mount Ida, is located in this province. Balıkesir province is famous for its olives, thermal spas, and clean beaches, making it an important tourist destination. The province also hosts immense deposits of kaolinite and borax, with some open-pit mines. The Kaz mountains are also threatened with the expansion of gold mining using cyanide which puts the villagers' lives, the agricultural economy, and tourism at risk.