This site, high on the cliffs approximately 1km west of the Longues-sur-Mer gun batterie, had a commanding view out to sea and the high ground made it ideal as a communications area.
Used by both the German Navy (Kriegsmarine) and air force (Lufftwaffe), Wn51 hosted a long-range radio navigation system known as Elektra-Sonne which boasted a huge range of around 1,600km to enable aircraft to pinpoint their location. This type of system was so accurate is was still being used up until 1990.

The site also employed a FuMB 21 Freya radar system for medium-range detection of incoming air and sea objects.
Nothing remains of these devices at the site today which continued to be a marine semaphore post after the war before becoming a private house, but you can still see a pair of Bf58c machine gun Tobruks protecting the rear of the site from inland attack.