If you are intrigued by Alain Delon, I would further suggest "Les felins" (Rene Clement / France / 1964), a beautifully shot french film noir, starring Jane Fonda.
And he also played alongside Jean Gabin in one of my favorite films "Two Men in Town" (deux hommes dans la ville / Jose Giovanni / 1973 / france, Italy). This is actually a neglected masterpiece and one of the most heartfelt denunciations of the death penalty (that also existed in France!) I've ever seen. Beautiful cinematography, very good editing and a gorgeous score by Philippe Sarde complement the memorable acting and a solid directing job. It also has Gerard Depardieu in one of his early supporting roles as a small-time crook 
Both films are on DVD in the US I believe.