Gavin and Madeleine's apartment building is "The Brocklebank" at 1000 Mason Street on Nob Hill, which still looks essentially the same. It is across the street from the Fairmont Hotel, where Hitchcock usually stayed when he visited and where many of the cast and crew stayed during filming. Shots of the surrounding neighborhood feature the Flood Mansion and Grace Cathedral. Barely visible is the Mark Hopkins hotel, mentioned in an early scene in the movie.
Here is a link to the wikipedia film entry which includes information on Vertigo filming locations:Read film information at Wikipedia
For more information about this and other Classic Movie Travels, see the book Film + Travel North America, South America: Traveling the World Through Your Favorite Movies