Alos or Halos (Ancient Greek: Ἅλος) was an ancient Greek city, located 10 km south from present-day Almyros. The city is mentioned by Herodotus as one of the places where the Persian king Xerxes stayed in the summer of 480 during his attack on Greece; Herodotus digresses upon a human sacrifice ritual. The site of the classical city, which was destroyed in 346 by Parmenio during the Third Sacred War, has been identified, but not excavated. A Byzantine fort is the last building phase from Antiquity.