Peterloon was designed by the architect William Adams Delano of Delano & Aldrich, the leading country-house architectural firm in the United States, and took over two years to build. The house is a combination of Georgian and Queen Anne styles and when finished had 36 rooms, 19 fireplaces, 21 baths, and included a wing of guest rooms. Originally sited on 1,200 wooded acres in Indian Hill, the house was built to rival the grandest houses of America and Europe.