📝 Note for collectors
I didn't save the exact location I bought my pin from here, but I remember that Rome is a city where it was more a problem of deciding which pin to buy and keep, than to where to buy one. Wasn't an issue to find one at all.
Google Maps
📍 Roma Imperium
Based on a Google Maps photo from 2018 (https://maps.app.goo.gl/8QJcMpcKUieTVcNeA, bottom right) they sell a variety of pins about Rome, Vatican and Italy - so most likely sell them now too.
🏙️ City pins
🌍 Country pins