Gripsholm Castle (Gripsholms Slott) is a castle in Sweden and is regarded as one of Sweden's finest historical monuments. It is located in the town of Mariefred by the lake Mälaren in south central Sweden, in the municipality of Strängnäs, about 60 km west of Stockholm.
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 (Gustav Vasa) in 1526. The King tore it down, and built a fortified castle with 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 John III Vasa and his wife Catherine Jagiellon in the castle. Their son Sigismund III Vasa, later the King of Poland and Sweden, was born there in June 20 1566.
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 part of the castle houses the National Collection of Portraits (Statens porträttsamlingar), the oldest portrait collection in the world.