The remains of the castle can be visited
Hausfreden Castle

The castle remains of Hausfreden, a former spur castle from the 14th century, are situated above the Leine near Freden in Lower Saxony. Once a strategically important point for monitoring the Leine valley.
History+
Hausfreden Castle was built in the mid-14th century by the Lords of Freden, who received permission from the Bishop of Hildesheim in 1344 to construct a fortification. In 1382, the builders sold half of the complex to the Welfs, who then pledged the castle to the Lords of Wettberg. From 1400 onwards, the succeeding Lords of Reden used the castle as a base for robber knighthood. An alliance of the Bishop of Hildesheim, Welf dukes, cities, and other nobles subsequently besieged the castle in May 1402. After a week-long siege and bombardment with a cannon, the castle was captured, razed, and never rebuilt. Archaeological investigations in 1962 unearthed ceramic fragments and iron pieces, confirming the 14th-century age of the site.
Image: https://de.wikipedia.org/wiki/Datei:Hausfreden_Mauerrest.jpg
Location: 51.9165, 9.9182