Derbent Fortress is an ancient fortification located in the city of Derbent, Azerbaijan. It dates back to the 6th century and is recognized as one of the oldest fortresses in the world. The fortress was strategically built to protect the region from invasions and control the passage between the Caspian Sea and the Caucasus Mountains. The fortress features impressive walls and towers, some of which are still well-preserved today. It has been designated a UNESCO World Heritage Site due to its historical significance and architectural value. Throughout its history, Derbent Fortress has served various empires, including the Persian Empire and the Arab Caliphate.