The earliest settlements date to around AD 700. Aalborg’s position at the narrowest point on the Limfjord made it an important harbour during the Middle Ages, and later a large industrial centre. Architecturally, the city is known for its half-timbered mansions built by its prosperous merchants. Budolfi Church, now a cathedral, dates from the end of the 14th century and Aalborghus Castle, a royal residence, was built in 1550.