To the casual observer of the Stp Ruine site near Neufchatel to the south of Boulonge-sur-Mer there isn’t much to see except the frontages of four R669 type casemates partially buried in the hillside.
However, the hillside hides a labyrinth of underground tunnels linking personnel shelters, command bunkers, and the gun emplacements in an underground network invisible from Allied eyes.
The four R669 casemates each featured 10cm guns and covered the vast area towards Hardelot Plage and its wide sandy beaches on the Pas de Calais west coast.
They also provided protection for the remarkable building cut deep into the hillside below at Stp Hasso, a massive torpedo and sea mine storage facility which even had its own dedicated railway line for transporting the weapons to the ports of Boulogne and Calais.
There were 44 underground storage areas and two tunnels for trains planned for Stp Hasso and today you can see around 15 areas which all feature a dog-leg design and ventilation systems to protect the explosives stored inside.
At Stp Ruine, most of the tunnel entrances have been sealed up over the past decade and are no longer accessible for safety reasons, plus the site has become a haven for rare bats so it is now illegal to enter the buildings and tunnels and disturb the new residents.
The former residents of the site built a lot of concrete here, including two R119 type HQ/Command bunkers, a R609 HQ bunker, R622 and R661 group shelters and first aid/hospital bunkers, Wellblech shelters, and a relatively rare R658 water storage bunker.