On the limited， 12×8 m， site it was required to build 4 meters from the street to the front and 4 meters to the back property line， thus only a 4 by 8 m strip could be built. The entire lot was excavated for the basement and three floors were built above ground， the entrance level and the two upper floors for bedrooms. Through openings in the floor of the ground level and the glazed ceiling of the rear courtyard， an open diagonal space is created facing south， allowing the sun to completely enter through the building. Once again， a diagonal space istensed by diagonal light. This time， with clockwork precision.