George Romero's "Dawn of the Dead" is not just one of the foundational films of the "zombie apocalypse" genre (which Romero invented), and not just a terrific blend of horror and social commentary. It is also a wonderful example of the wild, creative energy that drove so many low-budget independent films of the 1970's.
Romero's masterful editing, fast plotting, bloody, innovative special effects and efficient use of his abandoned-mall setting and tiny budget created this American cinema classic that Roger Ebert called "one of the best horror films ever made".
And now the director's cut is on YouTube.
On topic, this article from January: "Why 'Dawn of the Dead' Still Matters"
Enjoy!