San Marino, my 29th visited country, was surprisingly pretty. I am quite sure reaching the Old Town at dusk on a December afternoon helped.
How to reach San Marino: if you fly into Bologna, the easiest way is to rent a car and drive to San Marino (which’ll take you about two hours). There are a dozen parking lots in the main city, on Monte Titano; I recommend finding no. 11, from which a cable railway will take you directly to the top of the Old Town. Parking is 1.50 EUR/hour, and the cable railway leaves every 15 min and costs 4.50 EUR return.
Alternatively, you can get the shuttle bus from Bologna airport to Rimini, on the coast, and then a bus to San Marino from there.