It's difficult for me to really express why I admired this film so much. There is of course the amazing cast: Burt Lancaster, Alain Delon, Claudia Cardinale (appearing here the same year as her memorable performance in 8 1/2, talk about a good year!), and even real Sicilian royalty in the breathtaking 45 minute final scene. There is the graceful and beautiful imagery. Visconti nevers cuts for the sake of cutting, and often he lingers over a shot that only reveals its beauty and meaning over time. He gives us time to think, and to explore the image for ourselves.
So the film is formally a masterpiece, but what makes it even more special is the restrained and melancholy story it tells, one conveyed through small gestures and unspoken thoughts. A scene near the end of the film shows a few couples dancing away the final hours of a Ball as the sun rises. Trash covers the floor and the other Ball-goers doze on couches. There is a dying, fading glow to the Ball's dawn conclusion, acknowledging that the arrival of a new age entails the sad and slow death of another one. Lancaster, the titular "Leopard", the representative of a now defunct nobility, is spared the indignity of a death scene. He walks out of history under his own power.
And history goes on without him. This film remembers.