Benchmark on Lviv's City Hall
Somehow I only found out about this benchmark last week, so it wasn't included in my original post about benchmarks in Lviv. And I had walked by it thousands of times as it is located right on the Lviv's City Hall.
On the benchmark is "znak wysokości (Polish for "height marker"), an eagle (Poland's coat of arms), and the letters "P. N." It's possible "P. N." stands for "Polska Norma" (Polish Standard) or "Poprawka Normalna" (Normal Adjustment).
As it features the Polish coat of arms, it dates from the interwar period when Lviv was part of the Second Polish Republic.
image from here