oughly translated: "Royal Prussian Topographic Survey / meters above sea level"
Unfortunately the inscription of the actual elevation in the middle of the disc is missing. I don't know if it's lost or never was affixed at all.
But I found a photo of an intact benchmark of the same type at Wikipedia: http://commons.wikimedia.org/wiki/File:KoeniglPreussLandesAufnahme.JPG
The Preußische Landesaufnahme (Prussian Topographic Survey) was founded as an agency of the German Army in 1875 to produce maps for the Army, but soon it mainly performed civil topographic and geodetic surveys not only in Prussia, but in whole Germany (with exception of Bavaria).
Later it was renamed to Königlich Preußische Landesaufnahme (Royal Prussian Topographic Survey), which is the inscription on the benchmark.
When World War I broke out in 1914, it was dissolved, but in 1917 it was created again.
In 1919, after the war, it became a civil agency named "Landesaufnahme, Zweigstelle Berlin" (Topographic Survey, Berlin branch), and in 1921 it was renamed again to "Reichsamt für Landesaufnahme" (Imperial Office for Topographic Survey).…