It became a state museum in the 1970s and displays collections of paintings, furniture, textiles and tableware as well as books and weapons that amount to 20,000 items.

[1] The castle was built in the Baroque style between 1654 and 1676 by the wealthy military commander count Carl Gustaf Wrangel on a peninsula of Lake Mälaren between Stockholm and Uppsala.

The castle is a monument to the Swedish Age of Greatness, a period in the middle of the 17th century when Sweden expanded to become one of the major powers in Europe.

[3][page needed] The castle was converted into a permanent residence after the Second World War, when the von Essen family moved in.

[citation needed] The castle armoury and library are noteworthy, both founded on Wrangel's collections of weapons and books and enriched and enlarged by other 17th- and 18th-century aristocratic bequests, such as those by Carl Gustaf Bielke.

The original scale model of the castle, which the architect Caspar Vogel had made to demonstrate his plan to Count Wrangel, is also there.