This is the souterrain of Auberville.
The first entrance has a Tobruk for protection.
The second entrance is closed with bars, but the lower hatch was open.
With an entrance defence and a heavy door.
Wide and high corridors with several junctions.
There are different levels.
With or without stairs.
Maybe a sleeping room with bedhooks?
There is much paintwork. This might be an original iron cross.
This part was still under construction.
Nicely shaped cable duct.
The other entrance is also protected by a Tobruk.
The corridor to this Tobruk has a third entrance to the system.