Scenes from THE LAST DAYS OF POMPEII (1959)
This spectacular movie has several stand-out effects scenes, mainly the exploding volcano but it also has a good number of beautiful and subtle matte paintings. Above is the scene in the arena during the climax, with Steve Reeves and Christine Kaufmann. Below is how the location / set looked like. Mount Vesuvius was added in the background. Last image below: the screenshot of Pompeii and the volcano in the background is probably one of my favourite matte works. Absolutely beautiful and very subtle. Matte work by Emilio Ruiz del Río with Mario Bava (technical)!
IMO, one of the best matte paintings ever. It's simply beautiful.