Dating in 871, Tønsberg is commonly believed to have been the oldest Norwegian town and one of the oldest recorded fortified locations in Norway. According to Snorri Sturluson, Tønsberg was founded before the Battle of Hafrsfjord under which King Harald I of Norway united Norway under his rule. Tønsberg was an important trading center and site of Haugathing, the Thing (assembly) for Vestfold and one of Norway's most important place for the proclamation of kings.In 1253, King Haakon Haakonson set up a castle, Tunsberghus, at the location of the modern Tønsberg municipality.
In 1503, after the Kalmar Union collapsed, Norwegian attempts to rebel were suppressed by Danish forces. Tunsberghus fortress was destroyed by Swedish soldiers and disloyal local peasants.
Only a few ruins of the fortress are now left. The modern-day tower (Slottsfjellet i Tønsberg) was raised in 1888 as a memorial of the historic fortress. The present tower was built during 1888 as a memorial of the historic fortress. In 1971, local authorities improved the insulation. At that time new plaques were mounted inside the tower. On the sides are the gilded signatures of two modern Kings of Norway: Haakon VII (1 August 1906) and Olav V (1 July 1958).
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.