Koenig considered the Gantert House his most demanding commission; designing a home on an "un-buildable" on a steep, 45 degree slope. The architect answered the challenge by innovative design: prefabricated steel was brought by truck to the lower edge of the site, and hoisted by crane. The steel frame became its own scaffolding with all interior components installed from withing the structure.
In 2003, Koenig started an extensive renovation of the house, shortly before his passing. The work was completed under the direction of Architect James Tyler, Koenig's personal choice. Located at 6431 La Punta Drive in Los Angeles.