The current owner of Fior d'Italia
and the waitress who served me were so nice that I wish I could say something nice about the food. Granted, I only went for brunch, and perhaps that's not the best barometer of a restaurant's quality. Still, the over-salted baked polenta I had was served with a tomato sauce that tasted like it came from a can, not a good sign for a "red sauce" Italian restaurant serving what the owner describes as Italian comfort food. And the Italian sausages were eminently forgettable too.
The restaurant claims to be the oldest Italian restaurant in America, and I have no reason to doubt the claim. They first opened in 1886 (the year both of my maternal grandparents were born) and have had a number of locations over the years, all in or around North Beach, San Francisco's Little Italy as well as ground zero for the beat poets (can one still use "ground zero" in a non-9/11 context?). They're currently at the San Remo Hotel, a charming European-style hotel with shared bathrooms that I stayed at a number of times in the 'eighties until I graduated to private bathrooms.
San Francisco has quite a few truly excellent Italian restaurants, so unless you're writing a blog series about vintage San Francisco eateries I'd recommend you eat at one of those others.