Statement of Significance (as of designation - June 29, 1989):
Built in 1937-1938 for the President of Johnson's Wax Company, this large house was considered by its architect the finest (and most expensive) house he had built up to that date. Frank Lloyd Wright's design is so completely wedded to its site--rolling grassy slopes and shallow ravines--that it seems to grow naturally from the earth. Displaying what its author called the "eloquence of materials"--beautifully finished and integrated surfaces of wood, concrete and brick put together with respect and taste--it is the last of Wright's Prairie Houses. Currently, it is one of the most important educational and cultural conference centers in the Midwest.