Van de Velde designed the interior of the building entirely in a single concept: the design of the furniture, wall decorations and floor coverings, lamps and fabrics, crockery and cutlery was decided on after discussions with the owner. Various works of art were specifically selected to decorate the main rooms and the colour concept for the surrounding furnishings was selected to harmonise with them. The most significant of the paintings were Ferdinand Hodler’s "Auserwählter" (The Elected) in the reception room and Edouard Vuillard’s "Autumn in Paris" in the ladies’ room. Henri Matisse painted a triptych of tiles for the winter garden, and Jan Thorn-Prikker created the glazing on the staircase as well as the powerfully coloured stencils in the study. Sandstone reliefs by Hermann Haller flank the main entrance.

Van de Velde created a typical architect’s garden with a geometrical design and architectural spatial distribution. The southward garden axis, whose main element, the "Serenite" by Maillol, has unfortunately been destroyed, leads directly to the study. Nowadays this axis contains Othaus’s grave.

Karl Ernst Osthaus died in 1921 at the early age of 46 and as a result was unable to complete his "Gesamtkunstwerk Hohenhagen".

Osthaus has left many impulses on the town of Hagen. The memory of Osthaus is still kept alive north of Hohenhof. The Thorn-Prikker and the Milly-Steger streets remind visitors of the artists who were admired by Karl Ernst Osthaus. The painter and the sculptress belonged to the group of artists and intellectuals, who lived in the houses in his artists’ colony on the "Stirnband" road.

The "Walddorf" settlement is a further example of Osthaus’ creative ambitions. In 1907 Richard Riemerschmid was commissioned to design an estate consisting of 87 houses in the neighbourhood of Hohenhof. Unfortunately only six houses could be built along a section of a street. The completed fragment of the "Walddorf Settlement" gives some idea of the rustic character of the differently designed, small dwellings made of grey chalk sandstone with green windows.

Unfortunately the "garden suburb of Emst" also remained incomplete. It was intended for the less wealthy citizens of Hagen to enable them to lead a fulfilling life in the town and yet remain close to nature.