The Dryanovo Monastery is a functioning Bulgarian Orthodox monastery situated in the Andaka River Valley, in Bulgarka Nature Park in the central part of Bulgaria five kilometers away from the town of Dryanovo. It was founded in the 12th century, during the Second Bulgarian Empire, and is dedicated to Archangel Michael. Twice burnt down and pillaged during the Ottoman rule of Bulgaria, the monastery was restored at it present place in 1845. It was the site of several battles during the April Uprising of 1876.
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.