Imperial castle
An imperial castle or Reichsburg was a castle built by order of (or acquired by) the King of the Romans or the Holy Roman Emperor on land that was owned by the crown (Reichsgut). While in the early middle ages, in Francia, as well as in the early Holy Roman Empire, kings and emperors travelled around their realm with their itinerant courts, using their Kaiserpfalzen (imperial palaces) as transit stations and temporary residences, the weakly fortified pfalzen were replaced by imperial castles from the 13th century onwards.