[2][3] Gustav Vasa spent time there on several occasions, and his wife Margareta Leijonhufvud died at Tynnelsö Castle in 1551.

[3] In 1725, it was given to a Polish noblewoman, Anna Woynarowska[3] née Mirowicz,[2] who was niece-in-law of Ivan Mazepa, as payment for a debt that king Charles XII had to her husband.

In 1940, it became the property of the Royal Swedish Academy of Letters, History and Antiquities, who initiated a renovation scheme.

The gables were removed later, probably during the ownership of Anna Woynarowska, and further changes were made during the 19th century, for example the addition of the roof lantern.

The materials used, such as brick, were the most expensive of the day and reflect that the castle was used for representational and recreational purposes by the bishops of Strängnäs.

[1] The castle is surrounded by a former deer park, which since 2003 enjoys protection as a nature reserve and forms part of the EU-wide ecological network Natura 2000.