Tuna Church is a brick-built medieval church dating from the 1200s. The porch was added in the 1400s and arches in 1500s. The present tower was erected in 1877. The interior is decorated with frescoes (oldest date from the 1300s, choir murals were added in 1620). The remarkable wooden Madonna sculpture is probably a North German work from the 1400s.
References: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.