Mies' design principle of "less is more" and emphasis on functional amenities created a fine example of early functionalism architecture, a groundbreaking new vision in building design at the time. Mies used a revolutionary iron framework, which enabled him to dispense with supporting walls and arrange the interior in order to achieve a feeling of space and light. One wall is a sliding sheet of plate glass that descends to the basement the way an automobile window does. Mies specified all the furnishings, in collaboration with interior designer Lilly Reich (two armchairs designed for the building, the Tugendhat chair and the Brno chair, are still in production). There were no paintings or decorative items in the villa, but the interior was by no means austere due to the use of naturally patterned materials such as the onyx wall and rare tropical woods. The onyx wall is partially translucent and changes appearance when the evening sun is low. The architect managed to make the magnificent view from the villa an integral part of the interior.