Trondheim (ancient Nidaros), city and port in central Norway, on Trondheim Fjord. It is the seat of Sør-Trøndelag County. Trondheim is an archiepiscopal see, one of the largest cities in the country, and a commercial center for the surrounding agricultural area. The principal industries include shipbuilding, metalworking, and the production of processed foods and textiles. The 11th-century Nidaros Cathedral, erected over the tomb of King Olaf II, patron saint of Norway, is considered one of the finest ecclesiastical edifices in Scandinavia and is the site of Norwegian coronations. The University of Trondheim (1968) is here. Founded as Nidaros in ad 997, the city served as the capital of Norway until 1380. Trondheim was occupied by German troops during World War II (1939-1945). Population (2005 estimate) 157,813.