The Krukenburg is a castle at the Weser river. Remains of it can still be seen today, and we have visited the place a few times.
Remains of the chapel
Here is a short timeline:1126 A chapel, dedicated to St. John, is built on a mountain that overlooks the Weser valley and the village - later town - of Helmarshausen.1215-1220 A castle with fortifications is added which also serves as protection of the St. Benedict Abbey in Helmarshausen.1401 A building called Paderborner Haus is added to the castle area.1465 The castle is destroyed during the fights about the possessions of abbey, castle and town between the arch bishopseats of Cologne and Mainz, the diocesan town Paderborn, and the landgrave of Hessen (greedy lot, ain't they?).Chapel and keep
More about the Paderborn House can be found here