Volmarstein, Blankenstein - stone-rich area here ... But the hard coal is to be located much further north. But this is only mentioned in passing. The honorable Counts of the Mark liked to keep an overview and obviously had an eye for strategically good locations - really likeable these gentlemen from Altena.
The "Steel Time Travelers" Luise & Alfred: Burg Blankenstein
www.bochum-tourismus.de > Bochum entdecken > Kirchen u. besondere Orte
The area is accessible 24 hours a day.