What is pamarium?

Answer 1

I think you may be referring to what I have more commonly seen spelled as "palmarium" -which was, for the Romans, a sacred trench dug just inside the city walls which ran along its parameter to ensure the protection of all of the city's inhabitants by the gods/goddesses. Just as the city wall served to layout the geographic limits of the city so to did the palmarium define the protective region of the city's associated deities.