Schleswig-Holstein-Sonderburg-Glücksburg was a German ducal house that originated in the 16th century. It was part of the larger House of Schleswig and played a significant role in the history of northern Europe. The family ruled over various territories in Schleswig-Holstein, a region that is now part of modern-day Germany and Denmark. The most notable residence of the family is Glücksburg Castle, built in the Renaissance style. The castle is located near the town of Glücksburg and is a popular tourist attraction today. The house has connections to several European royal families, including the British Royal Family and the Danish Royal Family.