Kronstädter level
of the Kronstädter levels is the point of reference for the elevator system HN, that among other things in the GDR and the Soviet Union one used - contrary to the system NN used in western countries.
Already 1707 gave it in Russian crowning city a level service. 1840 became on suggestion of the hydraulic count M. F. Pure corner attached at the blue bridge over the Kronstädter Obwodnij channel a marking, which corresponded to the middle level of the water level of the Finnish sea bosom from 1825 to 1839.
