There's not a lot to do in the capital of San Marino in the evening. To be absolutely blunt, there's nothing to do there, unless you haven't walked around the fortress at all. And there is only one real restaurant there if you don't want (or cannot) leave the place for other Sammarinese communes down the hill (well, actually there are some places in the fortress still working in the evening - but nearly nothing else in the town outside the castle walls).

And the point is that, although this restaurant seems to be a natural monopoly, it is bothering itself to be something very good, as if there are a lot of competitors around. Great food, good service (even though most of staff speak only Italian and barely understand any other language - but even here I must admit that first evening we had a waiter speaking rather good Russian), warm atmosphere - and visibly a lot of locals coming there for dinner. Even if you don't stay in Citta, it's worth visiting this nice place.