This is one of six Marinepeilstände (MP) observation towers that were built on high points. They are the most obvious symbol of German construction. Each observation slit of a tower observed for one particular battery and was fitted with range finding equipment.  

Naval Range-finding Tower MP 3 at Pleinmont has 5 observation levels and had a radar unit on the roof,

The original rangefinders are still onsite and in working order. There is also access to a battery dolmen gun-site nearby.