A connection was planned for Phase 2, which also envisioned an entry several hundred meters to the rear, but was not pursued in time for the war.

[4] The blocks are linked by deep underground galleries, which also provide space for barracks, utilities and ammunition storage.

[5] In addition to the combat blocks, a series of detached casemates and infantry shelters surround Bovenberg, including The 1940 manning of the ouvrage under the command of Lieutenant Lambret comprised 228 men and 7 officers of the 161st Fortress Infantry Regiment.

[12] The Casernement de Boulay provided peacetime above-ground barracks and support services to Berenbach and other positions in the area.

After the Second World War it became part of the Mòle de Boulay, a strongpoint in the northeastern defenses against Soviet attack.