Erythres was named after the ancient city of Erythrae, the ruins of which are located 1.5 km east of the present town. The Greek National Road 3 (Elefsina - Thebes - Florina) passes through Erythres. The area south of Erythres is mountainous, with the Kithaironas to the southwest and the Pastra to the southeast. The area north of Erythres is characterised by the wide, flat valley of the Boeotian river Asopos, that flows to the east along the northern border of the municipal unit. This area is dominated by farmlands. Erythres is located 5 km east of Plataies, 6 km north of Vilia, 12 km south of Thebes and 44 km northwest of Athens.