SPQR makes it probably from Rome, but those lug cutouts were a style used by Giovanni Losa AFAIK, and he was not in Rome, so this may be one of the MANY he built for others who re-branded his work.
BTW he built very, very high quality frames!

Pleas post additional pix of the bottom of the Bottom Bracket shell and seat stay caps, plus of the brake bridge, if it has 'features', since that might confirm if this is one of Losa's. He built for a LOT of other brands (such as Cinelli) and they show up as "house-brands" all over Italy but also in Switzerland and Germany