Salvador Dalis Dream of Venus was installed for the 1939 world fair, he had built it in a pavillion filled with surreal scenes, he hired women to sleep in six hour shifts with 'venus's underwater dreams' shown in water tanks sorrounding the bed, even having 'mermaids' swim through them. It is considered by some as the begining of installation art. Dali created his own universe within the exhibition, hiring photographers and afterwards working with the photographs.
Rather than creating a single image on paper, he created a whole set in which people could immerse themselves before capturing the image from what was around him.
As with this image, I think it works so well as there are three parts to it - the installation and the model, Dalis apparently spontaneous painting on to the model during the exhibition and the photograph.
In this photograph you can see that the model is wearing a lobster, this is something that dali used throughout his later work; after this exhibition he hired various photographers-experimenting with 'seafood as underwear' trying to recapture the surreal nature of his installation.
I think what makes the image so interesting to me is that its not the original idea, it is more of an after thought, a byproduct of the exhibition but made into a piece of work in its own right.