I noticed that the recreation of Pompeii, the city had a wall around it. Given the Pax Romana, I was wondering why the wall- was it because Pompeii was an ancient city, built before Rome controlled the peninsula? Were all Roman cities walled? Were there roaming threats that the wall was designed to keep out?
Interesting, this is twice this question has been asked in the same day. I think that answer should help you. It's not at all uncommon to find walled cities from Roman Italy, even well after their walls no longer served any use. Pompeii wasn't destroyed centuries after the last time its walls had been useful either--the Social War, and Pompeii's revolt and defeat, had been a mere century in the past.