The Mission Inn Hotel & Spa in Riverside, California, began its storied history in 1876 as a modest, 12-room adobe boarding house known as the Glenwood Cottages. It was founded by Christopher Columbus Miller, but it was his son, Frank Miller, who transformed the property into a world-class resort. Over several decades and four major construction phases, the Inn evolved into a breathtaking architectural tapestry primarily defined by the Mission Revival style, though it also incorporates Spanish Colonial, Renaissance, and Mediterranean influences. Frank Miller’s passion for global culture filled the "castle" with a massive collection of bells, international art, and religious artifacts. Throughout the 20th century, the Inn served as a prestigious getaway for celebrities and ten U.S. Presidents, eventually earning its designation as a National Historic Landmark in 1977. Today, it stands as a monumental tribute to Riverside’s citrus-era prosperity and California’s romanticized architectural heritage.