Main guardhouse and jail for the 38 cm battery. The building, in red bricks, was built in 1941 and housed guardroom for the security guard of ten soldiers. Originally, the jail had six cells, but in 1943 it was expanded to 20 cells, as the crew of the fortifications now had grown to around 3000 soldiers.
After the war, the building was used as youth hostel and later as private residence.
The building was demolished in 1984