I'm sure there are more than a few sandwich shops on the planet that deserve to have their votes counted, so pardon my voting All'Antico Vinaio to be My Favorite On The Planet. Yes, it's really that wonderful.
The sandwiches are HUGE and really unique and delicious. The employees were over-the-top warm and friendly, handing out samples of goodies from behind the counter for us to try. We asked for a sandwich with salami, cheese and arugula -- and whatever else sounded good according to the sandwich guy -- and he made us great sandwiches which also included roasted eggplant....We asked him to recommend a red wine to go with it, which he did (and which was excellent.) The absurdly large and delicious sandwich was 5 euro.
For anybody visiting who wants a great sandwich, and a great experience, this is a must see.