The Forbach river drops out of Freudenstadt into a narrow forested valley known as Christophstal. From the 16th to the 19th century this was the industrial heart of the region: silver and lead mines, smelting furnaces, hammer mills, and the ironworks that supplied tools and weapons to the Duchy of Württemberg. Almost all of that is gone now — what remains are scattered foundations, a restored furnace house, information panels, and a mining adit you can peer into.
A waymarked Bergbaupfad (mining trail) leads down through the valley from the northern edge of Freudenstadt, taking about two hours one-way. It is one of the more interesting walks immediately from town: cool, shaded by mossy spruce, and a reminder that the Black Forest's history is industrial as much as bucolic. The trail continues north toward Baiersbronn for those wanting a longer day.