John D. Hertz, of rental car fame, discovered Trout Valley (then a part of unincorporated McHenry County) in the 1920s. He built a mansion, barns, and polo grounds on the banks of the Fox River, calling his new country estate Leona Farms. Famous landscape architect Jens Jensen designed its scenic landscape, fishing streams, and ponds. Here Hertz raised racehorses, including two Kentucky Derby winners, and hosted Gatsby-like parties for the rich and famous, including Myrna Loy, Will Rogers, and Walt Disney. Eleanor Roosevelt was once a guest too. In 1943, Hertz sold his estate to Otto...