Guaita Tower or Rocca Guaita is the oldest, largest, and most popular among visitors when it comes to the three towers of San Marino. Built-in the 11th century, this fortress has been guarding the heads of San Marino residents for many generations. It was used as a prison for a short time. Today, she is a favorite among the visitors who dedicate most of their time to visiting the historical sights of this country.