The flag of the Roman Empire featured several symbols over the years, prominently showcasing the SPQR brand

https://andersonuovb723.wordcanopy.com/posts/salute-to-service-flying-the-flag-for-those-who-served

The flag of the Roman Empire featured a number of symbols over the years, prominently showcasing the SPQR emblem, representing the Senate and People of Rome, reflecting its colossal territorial conquests and governance.