SIEGEN, a town of Germany, in the Prussian province of Westphalia, situated 63 m. E. of Cologne by rail, on the Sieg, a tributary entering the Rhine opposite Bonn. Pop. (1905) 25,201. The town contains two palaces of the former princes of Nassau-Siegen, a technical and a mining school. The surrounding district, to which it gives its name, abounds in iron-mines, and iron founding and smelting are the most important branches of industry in and near the town. Large tanneries and leather works, and factories for cloth, paper and machinery, are among the other industrial establishments.

Siegen was the capital of an early principality belonging to the house of Nassau; and from 1606 onwards it gave name to the junior branch of Nassau-Siegen. Napoleon incorporated Siegen in the grand-duchy of Berg in 1806; and in 1815 the congress of Vienna assigned it to Prussia, under whose rule it has nearly quintupled its population. Rubens is said to have been born here in 1577.

See Cuno, Geschichte der Stadt Siegen (Dillenburg, 1873).