The Holckenhavn Castle is a manor at Nyborg. It was earlier owned by Ellen Marsvin and Leonora Christina. Today, the manor is used for conferences and private events.

The Holckenhavn castle consists of both towers and rampart graves as it was built in a style inspired by the Renaissance. The knight hall can fit c. 200 people and the manor has its own chapel with space for 100 people.

Holckenhavn was built c. 1579. At the time, the noble family of Ulfeldt owned the properity and castle, whereas the area used to be called Ulfeldtholm. 

The castle was later bought by Ellen Marsvin, who renamed the castle as Ellenborg. Ellen Marsvin's grandchild and son in law, Leonora Christina and Corfitz Ulfeldt, inherited the castle, but was arrested for treason by Frederik III because of their involvement in the Dano-Sweden Wars.

The couple moved to Ellenborg efter their release from Hammershus on Bornholm, but were shortly after accused of high treason. Afterwards, the king confiscated Ellenborg.

In 1662, the Holck family took over Ellenborg and renamed it as Holckenhavn.

Holckenhavn castle is still owned by the Holck-family. The current proprietor is called Christina Hou Holck, who inherited the castle after her father’s death, when she was 16.

The castle is primarily used for conferences and private events today.