The term "Byzantine Castle" refers to fortifications built during the Byzantine Empire, which lasted from the 4th to the 15th century. These castles were strategically located to protect important cities and trade routes. They often featured thick walls, towers, and moats, designed to withstand sieges and attacks. Many Byzantine castles, such as the Castle of Chlemoutsi and Kastoria Fortress, showcase unique architectural styles that blend Roman, Greek, and local influences. These structures played a crucial role in the empire's military strategy and are now important historical sites, reflecting the rich cultural heritage of the Byzantine period.