It's the first full-size Van Gogh canvas to be discovered in 85 years.
'Sunset at Montmajour' was painted by the Dutch master in 1888 and unveiled at Amsterdam's Van Gogh Museum.
Director Axel Rueger says it was created during the artist's time in the south of France.
SOUNDBITE: Axel Rueger, director of the Van Gogh Museum, saying (English):
"It is from his most prominent period in his career and just to give you some context, it is the period during which he also painted 'The Sunflowers', 'The Yellow House', 'The Bedroom', some of his really most famous works."
The Norwegian owner stored the painting in an attic for decades after being told it was a fake - but now the lost Van Gogh can finally be fully appreciated.