Duchy of Westphalia
The wealth of forest, ore and water was the foundation on which the iron foundries, hammerworks, tinsmithies and tanneries were built. Moreover, the town's location between the Siegerland on one side and the Brandenburg-ruled Sauerland on the other favoured economic development. No later than the 18th century, Olpe and its outlying areas were one of the economic centres of the Duchy of Westphalia.