Gripsholm Castle is regarded as one of Sweden's finest historical monuments. A fortress was built at the location around 1380 by Bo Jonsson Grip, and belonged to his family until the confiscation of mansions and castles by King Gustav I in 1526. The King tore it down, and built a fortified castle with circular corner towers and a wall, for defensive purposes. Of the original medieval fortress, only the façade of a wall remains.
Since Gustav Vasa, Gripsholm has belonged to the Swedish Royal Family and was used as their residence until 1713. Between 1563 and 1567, King Eric XIV imprisoned his brother John and his consort Catherine Jagiellon in the castle. This was also one of the castles that King Eric was imprisoned in when John had overthrown him. John's son Sigismund, later the King of Poland and Sweden, was born in the castle on June 20, 1566.
The castle was again used as a prison between 1713 and 1773, before it was renovated by King Gustav III on behalf of his consort Sophia Magdalena. A theater was also added in one of the towers at this time.
Between 1889 and 1894, the castle underwent a heavy and controversial restoration by the architect Fredrik Lilljekvist during which many of the 17th and 18th-century alterations were removed. The largest change was the addition of a third floor; the planned demolition of a wing did not take place.
Today the castle is a museum which is open to the public, containing paintings and works of art. Part of the castle houses the National Collection of Portraits (Statens porträttsamlingar), one of the oldest portrait collection in the world.
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.