I believe that this is one of the greatest scenes ever filmed. The directed by Sergio Leone, featuring Clint Eastwood (Blondie) and Eli Wallach (Tuco). Music by Ennio Morricone.
I knew that the scene was filmed in Spain, but recently discovered the actual location of "Sad Hill Cemetery" (created for the movie by several hundred Spanish soldiers) . There are photographs of location then and now here.
The location from Google Maps:
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Looking at the same location in Google Earth provides a ground-level 3D view that matches the movie scenes quite well.