Serres Fortress is a historic fortress located in the city of Serres, Greece. Built in the 12th century, it was constructed to protect the region from invasions and has witnessed various historical events over the centuries. The fortress features impressive walls and towers, showcasing Byzantine and Ottoman architectural styles. Today, Serres Fortress serves as a popular tourist attraction, offering visitors a glimpse into the past. The site includes several well-preserved structures, such as the Byzantine church of St. Nicholas and the Ottoman mosque, making it a significant cultural landmark in the area.