castle (that also hosts a museum)
The Frankenberg Castle (in German, Burg Frankenberg, and sometimes spelled Frankenburg) is a castle in the Frankenberg area of Aachen-Mitte, itself a district of Aachen, Germany. Its name comes from the concept of a "Franke", which was a type of castle that did not owe fealty to any others. Of course, shortly after its construction, the lowland castle became a fief of a Graf (basically equivalent to Count), and later belonged to the Duchy of Jülich-Cleves-Berg. From 1961 until August 2010 the former water castle housed a museum that documented the history of the Aachen area, from its Stone Age flint mines, through the Roman thermal bath period, up to the Industrial Revolution.