Berehovo, or “Ukrainian Hungary,” is a town in Zakarpattia, located only 5 km from the Hungarian border. For most of its history it was part of Hungary, and so this heritage is still strongly visible in the cityscape (all street signs, many shop signs, etc., are in both Hungarian and Ukrainian). Today even most of the cars have Hungarian license plates.
All around the center I found these large metal knobs with the words “Magassági jegy,” which later I discovered means “elevation mark.” These date from before WWI.
More on benchmarks here.