This is the 4994th most frequent Polish word.
pomnikiem
"Pomnikiem" means "monument" or "memorial" in the instrumental case in Polish.
In this sentence, 'pomnik' is used as a noun referring to 'monument,' and 'pomnikiem' is the instrumental case reflecting encounter.
To jest pomnik, ale wczoraj spotkałem się z pomnikiem historii.
This is a monument, but yesterday I encountered a historical monument.
Here 'pomnikiem' is in the instrumental case again, in spatial context with the monument's position.
Spacerowaliśmy po parku z pomnikiem w centrum.
We were walking in the park with a monument at the center.
'Pomnikiem' is metaphorically used in the instrumental case indicating transformation into a symbolic monument.