Things to do in San Marino
You can see two of the three towers (as seen on the flag of San Marino) by purchasing the "Red Card" for ˆ4.50. The "yellow card" (ˆ3) only allows you to see one of the towers. You cannot enter the third tower (since there does not seem to be an entrance!)
Simply walk around the city. The narrow streets are full of surprises. The walkways wind up and down the hillside in an interesting way, inviting exploration.