Bergen Cathedral was first time mentioned in 1181. It retains its ancient dedication to St. Olaf. During the reign of king Haakon IV of Norway, a Franciscan friary was established near the church, then known as Olavskirken, or the church of Saint Olaf, which was incorporated in it. The church burned down in 1248 and again in 1270, but was reconstructed after both fires. In 1463, it burned down again, but this time it was not reconstructed until the 1550s, despite being declared the cathedral in 1537.
After the fires of 1623 and 1640, Bergen Cathedral received its current general appearance. The steeple on the nave was torn down, and the current tower was built. During the renovation in the 1880s by architect Christian Christie, the Rococo interior was replaced to give the interiors back their former medieval appearance.
A cannonball from the 1665 Battle of Vågen between the English and Dutch fleets remains embedded in the cathedral's exterior wall. The present organ at Bergen Cathedral, by Rieger Orgelbau, is from 1997. The organ is the fifth one in the cathedral's history; the first known organ was installed in 1549.
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.