The Basilica of the Holy Mother of God Eleusa is a former monastery church situated in the UNESCO World Heritage town of Nesebar in Bulgaria.
The church, on the northern side of the peninsula, was built in the 6th century. It is recorded until the 14th century, and formed part of a monastery complex. It is presumed to have been destroyed by an earthquake.
The northern part and the central nave had sunk into the sea, but in 1920 excavations and research began here, and the church is now well-preserved and partly restored.
It has three naves, three apses and a narthex, with two smaller apses on the north and south sides. It is 28 m long and 18 m wide.
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.