Fort Hommet 10.5 cm Coastal Defence Gun Casement Bunker, German coastal defense bunker in Castel, Guernsey.

The Fort Hommet 10.5 cm coastal defence gun casemate bunker is a restored Jäger-type Regelbau 600 casemate in Castel, built for a 10.5 cm K331(f) gun. Its plan places the gun room at 12 o'clock, spent shell room at 1, crew room with escape shaft at 3, anti-gas lock at 5, entrance at 6, two ammunition rooms at 7 and 9, and ventilation plant at 10.

Fort Hommet's headland held defences from 1680, with a Martello tower added in 1804. On 20 October 1941 Hitler ordered the Channel Islands fortified as part of the Atlantic Wall. This Jäger-type casemate, one of 21 built for 10.5 cm K331(f) guns, was begun in April 1943 after a railway link reached Vazon; four such casemates formed Stützpunkt Rotenstein.

The casemate is a Series 600 Regelbau Jäger design, named after the Organisation Todt officer who drew it up; four such structures stood at Fort Hommet as part of Stützpunkt Rotenstein. Its plan places the gun room at twelve o'clock, the spent shell room at one, the crew room with escape shaft at three, and two ammunition rooms at seven and nine.

The bunker sits on a headland overlooking Vazon Bay and opens for visitors on two afternoons per week from April through October. When planning your visit, check opening times in advance and note that access involves stairs and narrow interior passages.

The casemate was buried after 1945 and its entrance was only excavated in April 1993, when restoration began as part of Guernsey's fiftieth liberation project. It reopened in 1995 as a bare shell refitted for visitors.