The Duchy of Istria was a historical territory located in the region of Istria, which is now part of Croatia, Slovenia, and Italy. Established in the early Middle Ages, it was initially part of the Holy Roman Empire and later came under the control of various powers, including the Venetian Republic and the Austrian Empire. The duchy played a significant role in trade and cultural exchange due to its strategic location along the Adriatic Sea. Its capital was Pula, known for its well-preserved Roman architecture, including the famous Pula Arena. The duchy eventually ceased to exist as a distinct entity in the 19th century.