Citizen Kane.

I'm going to make a very bold statement, and here it is:

Citizen Kane is one of the most influential films of all time, if not the most influential.

Citizen Kane is the grandfather of film as we know it today. Not just film, but cinematography, lighting, set design, writing, and acting. 

For those of you unfamiliar, I will add a short video of Siskel and Ebert reviewing the film. To hear two experts speak about one of the greatest films of all time is truly inspirational.

To be frank, is it a mystery that this is one of my favorite films of all time?