Almost certainly a Cinelli (99% certainty in my eyes). Really awful paint job. The hole in the right rear drop-out points to a pre-1963 frame, which means the eyelets are also original and correct. The filing of the contour of the drop-outs is also correct for Cinelli, as are the BB, lugs and fork crown. The only thing that makes me hesitant about the identification is that it has not been confirmed that it uses the 26,2 seatpost. I have seen (and own) a number of other bikes from the 50's and 60's that used the same lugs and fork crown. Apparently, Cinelli sold them to certain select framebuilders. Others cast their own lugs.
Another appetizing element is the Cinelli headset that all by itself would bring a very pretty penny.
I believe that this frame was sold on ebay not that long ago with very
poor pictures and there was some debate at teh time as to whether it truly was a Cinelli.