Rome is studded with cannon balls (2022)

Stockholm also has famous canon balls lodged on buildings in the old town: https://www.atlasobscura.com/places/stortorget-cannonball

They are supposed to be from the Blood Bath that happened there in the 16th century when Swedes and Danes still enjoyed killing each other frequently, but no wall survives this long with a metal ball in it, hence that’s apparently a fake thing by some smart 18th century building owners.

Fort Pulaski in Savannah, Georgia also has cannonballs embedded in the brick walls: https://en.wikipedia.org/wiki/Fort_Pulaski_National_Monument

Or Rome is the set of a real-life Truman Show.