Blockhaus d'Éperlecques

The Blockhaus d'Éperlecques is a Second World War bunker, now part of a museum, near Saint-Omer in the northern Pas-de-Calais département of France, and only some 14.4 kilometers north-northwest from the more developed La Coupole V-2 launch facility, in the same general area.

The bunker, built by Nazi Germany under the codename Kraftwerk Nord West between March 1943 and July 1944, was originally intended to be a launching facility for the V-2 ballistic missile. It was designed to accommodate over 100 missiles at a time and to launch up to 36 daily.

Source: Wikipedia