Over and beyond the actual building, Mies van der Rohe and his partner at that time, the designer and decorator Lilly Reich also saw to the interior design. The floors are made of walnut or oak and the window embrasures and radiator covers – likewise made of walnut or oak – are still preserved. Glass display cabinets and dressers (nowadays concealed) were set flush with or two-thirds of the way into the walls. A flexible wooden wall in Haus Lange allowed the dining area to be separated from the hall. The details extended to the overhead lights, the door handles and the cupboard knobs. The picture rails all along the walls demonstrate even today that the former owners, Lange and Esters, were themselves contemporary art collectors and hanged paintings in their rooms.
Both Hermann Lange and Dr. Josef Esters were directors of Verseidag, a union of several textile companies from Krefeld. Hermann Lange was also a member of the Deutscher Werkbund. Source
(The extraordinary door is made of a tropical wood.)