From the year 1225, the existence of a castle complex in Westerwinkel was documented. A defiant water system must have existed there, protected by a double trench system with ramparts, testified – for the time of the Thirty Years War – so high that they almost completely concealed the lower window row. However, a fortification must have existed at this location at an earlier point in time.
For example, Count Arnold von Altea-Isenberg, who was also allowed to lead the title count of Hövel, was in possession of a weir in the area of Westerwinkel. Westerwinkel belonged until about the year 1000 to the county of Werl and then, depending on which of the two theories one follows (cf. the contribution counts of Hövel), either to the counts of Arnsberg or directly to the counts of Hövel over. After the inheritance (from Werl or Arnsberg), Westerwinkel was either 1003 or after 1124 an integral part of the county of Hövel. Located on the North Rim of the Werler or Höveler County, Westerwinkel together with falter was a solitary outpost on the edge of the area of interest of Münster.
The strategic importance of the site should therefore be reciprocal to the number of sources obtained, which makes the existence of a weir in this period probable for the entire period of existence of the counties Werl and Hövel, but not provable. This is all the more true as there is no building material from the original castle complex and no one can say how the castle complex originally looked. At the time of the Werler reign, however, already existed the village of Bern, which is now part of the Ascheberg, in the immediate vicinity of Westerwinkel (Bern is historically mentioned for the first time at 889 in the books of the monastery at the Ruhr. For its owner, it is likely that the need to take possession of this property in the northern rim of the county against possible invaders. In addition, it was situated on the old Commercial Road Münster – Dortmund – Cologne, today’s B54, which led through Berne, which underlines the strategic importance of the square.