The late antiquity and medieval Palmatis fortress is placed at the east end of Onogur village. The Roman road between Durostorum and Marcianopolis used to pass nearby. The fortress is situated on a high plateau, lowering down to the northeast towards the dry valley. The Early-Christian basilica from the time of Emperor Justian the Great has been revealed in Palmatis fortress.
The Walls of Constantinople are a series of defensive stone walls that have surrounded and protected the city of Constantinople (today Istanbul) since its founding as the new capital of the Roman Empire by Constantine the Great. With numerous additions and modifications during their history, they were the last great fortification system of antiquity, and one of the most complex and elaborate systems ever built. They were also the largest and strongest fortification in both the ancient and medieval world.
Initially built by Constantine the Great, the walls surrounded the new city on all sides, protecting it against attack from both sea and land. As the city grew, the famous double line of the Theodosian Walls was built in the 5th century. Although the other sections of the walls were less elaborate, they were, when well-manned, almost impregnable for any medieval besieger.