Grosnez Castle is a ruined castle built by Sir John des Roches around 1330. The castle's purpose was to provide local farmers with a place of refugee from French attacks. The French captured however the castle in 1373 and 1381. The castle was probably demolished around the time of the French occupation of Jersey (1461–1468). In 1483 the Seigneur of St Ouen was allowed to fortify his manor house and it is unlikely he would have been given permission if Grosnez was still in use. In 1806, a naval signal station was established at Grosnez to send messages to Guernsey.
The castle's position on a clifftop 60 m above the sea means that the natural features of the site protect it on three sides. A ditch dug into the rock provides protection on the fourth side. The remains of ruined walls, mostly footings, are still present. A drawbridge and portcullis protected the gatehouse, which is the only substantial surviving remnant, and would have made it difficult to capture. There are traces of six simple buildings.
The name comes from the old Norse words for 'grey headland' - grar nes - an accurate description of the site when seen from the sea, rather than from the French for big nose. A nearby headland to the west has a similar name, Rouge Nez.
References:Kakesbeck is one of the largest medieval fortifications in Münsterland and the oldest castle in Lüdinghausen. The imposingly grown complex originated in 1120 as a motte, a small hilltop tower castle. After numerous changes of ownership, the castle was extended onto two islands, but it was not until the 14th century that it underwent significant alterations and extensions under the von Oer family. The estate experienced its heyday in the middle of the 18th century, when it covered an area of almost one square kilometre and consisted of five further outer castles in addition to the core castle, which were secured by ramparts and moats.
The well-maintained condition of the castle today is thanks to the late Wilfried Grewing, the former lord of the castle. The foundation named after him has been particularly committed to preserving the property since 2020.