Kaiserpfalz

The term Kaiserpfalz (, "imperial palace") or Königspfalz (, "royal palace", from Middle High German "phal[en]ze" to Old High German "phalanza" from Middle Latin "palatia" [plural] to Latin "palatium" "palace") refers to a number of castles and palaces across the Holy Roman Empire that served as temporary, secondary seats of power for the Holy Roman Emperor in the Early and High Middle Ages. The term was also used more rarely for a bishop who, as a territorial lord ("Landesherr"), had to provide the king and his entourage with board and lodging, a duty referred to as "Gastungspflicht".
Origin of the name.
"Kaiserpfalz" is a German word that is a combination of "Kaiser", meaning "emperor", which is derived from "caesar"; and "Pfalz", meaning "palace", and itself derived from the Latin "palatium", meaning the same (see palace). Likewise "Königspfalz" is a combination of "König", "king", and "Pfalz", meaning "royal palace".
Description and purpose.
Like their peers in France and England, the medieval emperors of the Holy Roman Empire did not rule from a capital city, but had to maintain personal contact with their vassals on the ground. This was so-called "itinerant kingship"; a sort of "travelling kingdom" ("Reisekönigtum").
Because "pfalzen" were built and used by the king as a ruler within the Holy Roman Empire ("rex Romanorum (Römischer König)"), the correct historical term is "Königspfalz" or "royal palace". The term "Kaiserpfalz" is a 19th-century appellation that overlooks the fact that the king did not bear the title of the Roman Emperor (granted by the Pope) until after his imperial coronation. Unlike a "pfalz", where the itinerant ruler enacted his sovereign duties, a royal estate or "Königshof" is only an economic estate owned by the king, which was only occasionally used by the king on his itinerary.
Unlike the common notion of "palace", a "pfalz" was not a permanent residence but a place where the emperor stayed for a certain time, usually less than a year; itineraries suggest that the monarch rarely would stay for longer than a few weeks. Moreover, they were not always grand palaces in the accepted sense: some were small castles or fortified hunting lodges, such as Bodfeld in the Harz.
But in the main they were large manor houses ("Gutshöfe"), that offered catering and accommodation for the king and his many retainers, often running to hundreds of staff, as well as numerous guests and their horses. In Latin, such a royal manor was known as a "villa regia" or "curtis regia." They were located either near the bishop's residences, near important abbeys, near towns the king held or in the countryside in the middle of royal estates. "Pfalzen" were generally built at intervals of 30 kilometres, which represented a day's journey by horse at that time.
At a minimum, a "pfalz" consisted of a "palas" with its Great Hall or "Aula Regia", an imperial chapel ("Pfalzkapelle") and an estate ("Gutshof"). It was here that kings and emperors carried out the business of state, held their imperial court sessions and celebrated important church festivals. Each was administered by a count palatine, who executed jurisdiction in the emperor's stead. One of the most important of them would eventually rise to the title of Prince-elector.
The "pfalzen" that the rulers visited varied depending on their function. Especially important were those palaces in which the kings spent the winter (winter palaces or "Winterpfalzen"), and the festival palaces ("Festtagspfalzen"), Easter being the most important and celebrated at Easter palaces ("Osterpfalzen"). The larger palaces were often in towns that had special rights (e.g. imperial immediacy), but could also be bishop's seats or imperial abbeys.
In the Hohenstaufen era of the Roman-German kingdom, important imperial princes began to demonstrate their claims to power by building their own "pfalzen". Important examples of these include Henry the Lion's Dankwarderode Castle in Brunswick and the Wartburg above Eisenach in Thuringia. Both buildings followed the basic design of Hohenstaufen "pfalzen" and also had the same dimensions.
List of Holy Roman Imperial palaces.
Examples of surviving imperial palaces may be found in the town of Goslar and at Düsseldorf-Kaiserswerth.