Short answers, pulled from the story.
Hearst Castle was conceived by William Randolph Hearst and designed by architect Julia Morgan. Construction ran from 1919 to 1947, when Hearst's declining health forced him to leave the estate for the last time.
Hearst Castle is in San Simeon on California's Central Coast, approximately 250 miles from both Los Angeles and San Francisco. It sits at an elevation of 1,600 feet atop a hill of the Santa Lucia Range, about five miles inland from the Pacific Ocean.
The main house, Casa Grande, has 42 bedrooms, 61 bathrooms, and 19 sitting rooms across 68,500 square feet of floor space. The complex also includes 127 acres of gardens, an indoor and outdoor swimming pool, tennis courts, a movie theater, and an airfield.
Hearst Castle was the direct inspiration for Xanadu in Orson Welles's 1941 film Citizen Kane, and William Randolph Hearst was the main model for Charles Foster Kane. Hearst tried to stop the film's premiere and used his media empire to damage its circulation after it was released on the 1st of June 1941.
Guests at Hearst Castle included Calvin Coolidge, Winston Churchill, Charlie Chaplin, Cary Grant, the Marx Brothers, Charles Lindbergh, Jean Harlow, Clark Gable, Greta Garbo, and Buster Keaton. Churchill and P. G. Wodehouse were among the notable international visitors.
Hearst Castle opened to the public in June 1958, after the Hearst Corporation donated the estate, its gardens, and many of its contents to the state of California. It was added to the National Register of Historic Places on the 22nd of June 1972 and designated a National Historic Landmark on the 11th of May 1976.