I am not certain of the brand, but I am fairly certain you have an Italian Sport bike. They were made by all the major manufacturers, and many or the minor manufacturers. Typically a straight gauge tubing, they had upright bars, sometimes condorino style. They usually had a single chainring with a 3-5 speed rear, depending on its age. Internal cable routing and pump pegs were also standard on a Sport bike.

The pump pegs behind the seat tube is a good clue. Bianchi had them. Bianchi also had the seat binder bolt on top. And the seat stay attachment says Bianchi. But without an integrated headset, I don't think it is a Bianchi. Also, the lugs aren't screaming Bianchi to me either.

Back to the pump pegs. Behind the seat tube placement ended by the mid 50s. I'm fairly certain it is post war, but I am not certain. My best guess would be right around 1950. But it could be as early as the mid 30s.

Try cruising Paulo's site for an ID. With some time, you can probably find a match.

Bici Classiche