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:Trenčín Castle is relatively large renovated castle, towering on a steep limestone cliff directly above the city of Trenčín. It is a dominant feature not only of Trenčín, but also of the entire Považie region. The castle is a national monument.
History of the castle cliff dates back to the Roman Empire, what is proved by the inscription on the castle cliff proclaiming the victory of Roman legion against Germans in the year 179.
Today’s castle was probably built on the hill-fort. The first proven building on the hill was the Great Moravian rotunda from the 9th century and later there was a stone residential tower, which served to protect the Kingdom of Hungary and the western border. In the late 13th century the castle became a property of Palatine Matúš Csák, who became Mr. of Váh and Tatras.
Matúš Csák of Trenčín built a tower, still known as Matthew’s, which is a dominant determinant of the whole building.