The 7 minute, single take, multi-floor hospital shootout from John Woo's Hard-Boiled. No cuts... it's pretty amazing to watch. Every bullet was choreographed and accounted for.
For awesome fight scenes, look no further than Jet Li in Fist of Legend... one of my all-time fave martial arts flicks. Tony Jaa in Ong-Bak is pretty badass too.
I recently watched Shinobi (adapted from the manga, Basilisk) and it was impressive. Every ninja had their own special technique. Crouching Tiger can't be ignored either. Same for House of Flying Daggers, Hero, Iron Monkey, and The Legend of Drunken Master. Drunken Master is by far Jackie Chan's best flick. The fight scenes in this movie are unbelievable.
The Allieds landing in Normandy in the beginning of Saving Private Ryan is something to behold. As are the battle sequences in BRAVEHEART.
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