Castelsardo is a picturesque and safe town in Italy. It is often described as welcoming, with locals known for their friendliness towards visitors. The crime rate is relatively low compared to many other destinations. However, like anywhere else, it's always recommended to take standard safety precautions such as not displaying expensive jewellery or money, avoiding unlit and deserted areas at night, and keeping an eye on your belongings at all times, especially in crowded places.