Barntrup and Alverdissen were founded by the Earl of Sternberg in the year 1220. Originally Barntrup was called Barendorf and was a village at the Schratweg. Between 1317 and 1359 Barntrup was built on the highest point of the "Thornesberg" which is 189 m high above sea level. This is the central point of Barntrup.
Kerssenbrock Castle (also called Schloss Kerssenbrock or Barntrup Castle, see picture) was constructed from 1584-1588 by Anna von Kerssenbrock (maiden name Anna von Canstein). Her husband, Franz von Kerssenbrock, had been a mercenary in the French Wars of Religion, where he had made much money. The Kerssenbrock family was one of the main noble families in the region.