Holstein-Gottorp or Schleswig-Holstein-Gottorp is the historiographical name, as well as contemporary shorthand name, for the parts of the duchies of Schleswig and Holstein, also known as Ducal Holstein, that were ruled by the dukes of Schleswig-Holstein-Gottorp. Other parts of the duchies were ruled by the kings of Denmark. The territories of Gottorp are located in present-day Denmark and Germany. The main seat of the dukes was Gottorf Castle in the city of Schleswig in the duchy of Schleswig. It is also the name of the ducal house, which ascended to several thrones. For this reason genealogists and historians sometimes use the name of Holstein-Gottorp for related dynasties of other countries.