At a ball at the fortress of Bergenhus he met Karen Axelsdatter Mowatt (1630-1675), sole heiress to the largest fortune in the country at the time.

[2] In 1661, Ludwig Rosenkrantz started building his own country house in Rosendal and completed this in 1665.

In 1678, King Christian V of Denmark gave the estate the status of a barony - the only one of its kind in Norway.

Authors Henrik Ibsen, Jonas Lie and Alexander Kielland and painters Hans Gude and Anders Askevold visited Rosendal often.

Ludvig Holgersen Rosenkrantz received a baronial patent (Friherrepatent) in 1678 from King Christian V. The successive barons were: In 1749, Bishop Edvard Londemann of Rosendal received a patent of nobility under the name Londemann af Rosencrone.

The holders of this title were: A member of the Hoff family in the Bohemian nobility was naturalized as a Danish-Norwegian nobleman in 1778.