Owing to its location on the Limfjord, Denmark’s fourth-largest city has been an important and prosperous harbour since the Middle Ages. A major industrial and commercial centre, it exports cement, grain and fish, and has become famous for its delicious mussels and oysters and its locally-produced akvavit. Aalbrog also houses a university and an important air force base. Its tourist attractions include timber-framed Aalborghus Castle, the Renaissance-style house of merchant Jens Bang, and Aalborgtarnet, the 55-metre observation tower with a restaurant on top. Most visitors come for the carnival in May, which features performances for children, a carnival band contest, lots of dancing in the street and fireworks.