U antičkom periodu na području Blagaja postojala je ilirska utvrda i vrlo značajan castrum (vojna utvrda) izgrađena u 4. i 6. vijeku. Grad se prvi put spominje u spisima tek od 15. vijeka i bio je rezidencijalno mjesto bosanskih vladara.
During the Antiquity era in the area of Blagaj there was an Illyrian fort and a very important castrum (military fort) built in the 4th and 6th century. The first time the city is mentioned is in manuscripts from the 15th century when it was a residential place of Bosnian rulers.
