Many of the earlier houses are the legacy of the feudal "heerlijkheid" system. The Dutch had a manorial system centred on the local lord's demesne. In Middle Dutch this was called the "vroonhof" or "vroenhoeve", a word derived from the Proto-Germanic word "fraujaz", meaning "lord". This was also called a "hof" and the lord's house a "hofstede". Other terms were used, including "landhuis" (or just "huis"), a "ridderhofstad" (Utrecht), a "stins" or "state" (Friesland), or a " havezate" (Drente, Overijssel and Gelderland). Some of these buildings were fortified. A number of castles associated with the nobility are found in the country. In Dutch, a building like this was called a "kasteel", a "slot", a "burcht" or (in Groningen) a "borg".