Strongpoint Stp89 Fulda houses one of the largest bunkers in the port town of Calais, a structure known as a Dombunker.
At 80 metres long and with a roof constructed from 2.5metres of reinforced concrete, this huge structure was designed to protect a K5 railway gun (like the one on display at the Batterie Todt Museum in Audinghen) which operated in this area during WW2.
There were three Dombunkers built in the area and all three survive today, although one is usually off limits to visitors due to their locations on industrial sites. The one in nearby Wimereux is in a housing estate and can be viewed from the street.
This site - on the western outskirts of Calais - also features a large ammunition storage bunker and observation/personnel shelter.
K5 railway guns were positioned here from 1940 onwards originally to provide fire support for Operation Sealion (the German invasion of Britain) and later to fire 28cm shells across the English Channel to Dover.
Across the road from the Dombunker – now covered by allotments - were over a dozen personnel shelters for the crew manning the railway gun along with anti-aircraft gun positions.