OB (zerst.) is a military bunker located in northern France, near the coast. The designation 'OB' typically refers to 'Objekt' in German military terminology, while 'zerst.' is an abbreviation for 'zerstört' meaning 'destroyed' in German. This suggests the structure was likely part of German defensive fortifications from World War II, possibly damaged or destroyed during Allied operations in the region.
The coordinates place it in the Pas-de-Calais department, an area heavily fortified during the Atlantic Wall construction.