The Krannan Tower is a medieval tower in the heart of the city, the only remaining part of a massive Danish fortress that once stood in the city. The first mention of the fortress in archaeological manuscripts dates back to the year 1310, and it was built at the time to fortify the Scandinavian borders. The tower is considered one of the most important attractions in Sweden, and it is visited by fences from all over the world. Visitors will be accompanied on their journey through the tower with a guide who will explain to them about its long history.