Unregistered

I recently moved into a house where the owner left much of their things behind. I found a watercolor painting of Florence, Italy. It is a city scape type painting, and each building is numbered, with its description at the bottom. It says what I'm assuming to be the artist's name as "Sergio Calosi." Does this sound familiar to anyone? Does anyone have an information? I am extrememly curious about the piece.

Thanks!