GUELDERS, or Geldern, a town of Rhenish Prussia, in the government district of Düsseldorf, chief and only town of the circle of Geldern, is situated on the Niers, 28 miles N.W. of Düsseldorf. Its industries include the manufacture of cloth and hats, wool-spinning, and wool, silk, and linen weaving. It has a Catholic and a Protestant church and two convents. The town was built in 1097, and was till 1343 the residence of the counts and dukes of Guelderland. It was fortified by Philip II., but its fortifications were razed by Frederick II. of Prussia in 1764. The population in 1875 was 5184.