Back Castle Cornet CEB Cornet Rock German Château Cornet French Castle Cornet Italian Корнет (замок) Russian Castle Cornet Swedish Kornet qalʼasi Uzbek 科內特城堡 Chinese
| Castle Cornet | |
|---|---|
| Part of Guernsey, Channel Islands | |
| Saint Peter Port Harbour, Saint Peter Port | |
 Castle Cornet stands on the former tidal island of Little Roussel. | |
 Location of Cornet Rock (red) within Saint Peter Port (white) | |
| Type | Norman castle with keep |
| Height | Up to 13 metres (43 ft) |
| Site information | |
| Owner | Bailiwick of Guernsey |
| Open to the public | Yes |
| Condition | Partially restored |
| Site history | |
| Built | c. 1206–1256 |
| In use | Until mid 19th century |
| Materials | Diorite Ashlar Mortar Timber |
| Battles/wars | French Invasion of 1338 English Civil War |
| Events | Hundred Years' War Napoleonic Wars German Occupation of Guernsey |
Castle Cornet is a large island castle in Guernsey, and former tidal island, also known as Cornet Rock or Castle Rock. Its importance was as a defence not only of the island, but of the roadstead. In 1859 it became part of one of the breakwaters of Guernsey's main harbour, St Peter Port harbour.