Answer
The answer is Glücksborg Castle, a Renaissance-style castle located in the town of Glücksborg in Schleswig-Holstein, Germany. It was built in the 16th century by Duke Johann the Elder of Schleswig-Holstein-Sonderburg and is known primarily for its association with the famous portrait of Christian III, King of Denmark, painted by renowned Renaissance artist Jacob Binck in 1533. The painting currently resides in Rosenborg Castle in Copenhagen, Denmark.