"The Godfather" trilogy was apparently running nonstop on Thanksgiving, and while I've seen them all, I got sucked into the first one and had to watch it all the way through the bloody baptism scene.
We were talking about the locations, and most of them are real places, generally on the East Coast. This site has a great list of where everything is.
Most interesting to me: The pink L.A. mansion where Jack Woltz finds the horse's head in his bed. The interior was filmed at Falaise, a mansion built for the Guggenheims. But the more West Coast-looking exterior belongs to a former William Randolph Hearst home, that apparently went on the market in 2007 for $165 million. It also served as Whitney Houston's estate in "The Bodyguard," the site says, and I cannot verify that because I choose never to see that movie.
The creepy hospital where Michael gets young baker Enzo to help him pretend they have guns and are guarding his father also has two locations. The exterior was Lincoln Medical Center in the Bronx, the site says, while the super-eerie deserted interior, which I swear is in every horror movie set at a hospital ever, is the New York Eye and Ear Infirmary in the East Village.