Duluth occupies a location at the western end of Lake Superior, adjacent to Superior, Wisconsin. Originally settled by the Sioux and Chippewa, French fur traders and explorers Radisson and Groseilliers were perhaps the first white men to see the present site of Duluth, Minnesota. Following them was Daniel Greysolon, Sieur du Lhut, the French adventurer for whom the city is named. In 1817, John Jacob Astor established an important fur-trading post on the banks of the St. Louis River at Fond du Lac, a name which means "head of the lake" in French. Fond du Lac was the first permanent white settlement in the Duluth area. In 1856, Duluth was platted and in 1878, it was incorporated as a city. The financier Jay Cooke made it the terminus of his Great Northern Railroad after the Civil War and the town prospered. After the discovery of ore in the Mesabi Range, iron ore became one of Duluth's principal products. By 1900, the Mesabi Range was the most extensive iron ore field on earth. The first railroad to reach Duluth was the Lake Superior and Mississippi Railroad in 1870. The construction of the Duluth Ship Canal through Minnesota Point in 1871 provided a further boost to Duluth as a port. The timber industry grew as the forests of Michigan were gradually depleted, reaching its peak around 1902. The University of Minnesota-Duluth has a rich history with origins dating back to 1895 when the Minnesota Legislature created the Normal School at Duluth. It later became the Duluth State Teachers College in 1921, and in 1947 it became a separate part of the new University of Minnesota.To accommodate GIs returning from World War II, construction of the new campus began in 1948 where it stands today. The American castle Glensheen was built between 1905 and 1908 for Chester A. Congdon and serves as an example of Duluth history, a city that once boasted the most millionaires per capita of any city in the world.Glensheen is an English country-style estate built on seven acres and has retained its original condition. The estate was deeded to the University of Minnesota by Congdon's heirs in 1968 and was opened to the public for tours in 1979. The whaleback steamer, a ship designed for use on the Great Lakes, was developed in Duluth. During World War II, more than 300 ships were built in Duluth. As high-grade iron ore became scarce, it was replaced by the lower-grade taconite ore, along with coal and grain. The development of the St. Lawrence Seaway opened up world markets within the reach of Duluth ships. Today, Duluth remains one of the most important centers of shipping on the Great Lakes.