In a little alley called Schering Rosenhanes Gränd there is large rock wall. In this wall there is a metal hatch. Behind the hatch there is a safe. Inside the safe there is a small silver rod placed in a wall at exactly 11.8 meters above the sea level. This once was Sweden’s official ordnance datum, main vertical reference point. Maps created with the help of this datum were for a long time used exclusively by the government agencies and military service. The place was chosen for convenience, as the general staff responsible for this worked nearby.
This datum is no longer in use and Amsterdam Ordnance Datum is the main reference point for Europe today.
Note: you can see the rock and the hatch, but you cannot see what’s inside.
