Billie Holiday singing "You can't take that away from me"; partly because of the memories it triggers of when I first heard it at Cambridge, and partly because it sums up what is important to somebody who is trying to write novels.
The Cherry Orchard - Chekov just has this wonderful ability to be able to make things happen under the surface which are different to what is actually happening on the surface.
Lake Nemi, about 25 miles outside Rome. It was the starting point for Fraser's The Golden Bough. I used it in my novel Augustus. It's one of the world's numinous places; a magical place. The entrance to the underworld is supposed to be beside the lake, and it really does give you the feeling that it might be.
Thorold Dickinson's version of the Pushkin story, The Queen of Spades. One of the most frightening scenes that I remember is the sound of the footsteps of the ghost of the princess as she comes to give the hero the secret of the cards. I only saw it once in 1948. I don't know why it's so frightening; it just is.
Anything by Caravaggio, particularly the St Matthew paintings in the church of S Luigi dei Francesci in Rome. I always feel that there is a novel to be written about some of his models.
`Antony', Allan Massie's fourth novel in his Roman Quartet, is published by Sceptre at pounds 6.99