A landscape by Albrecht Altdorfer that has never been recorded in the artist's catalogue raisonné will come to auction at Sotheby's in London on 9 December 2026, carrying an estimate of £3 million to £5 million. The small wooded scene, painted around 1520 and centred on a rainbow over a rocky outcrop crowned by a castle, is only the third known oil landscape by the German Renaissance master.

The picture has been held in the same Swiss private collection for decades. It was bought in 1957 by the consignor's father from the House of Harrach, the Austrian aristocratic family, and it has not been seen publicly since. Painted in oil on parchment laid on panel, it is the smallest of Altdorfer's landscapes, yet it carries the dense, visionary atmosphere that made him one of the most original painters of the northern Renaissance.

Altdorfer's landscapes are exceptionally rare at auction. The last example to appear on the market was in 1980, when the National Gallery in London paid £2.4 million for one, a sum worth about £13.4 million today. Altdorfer was a leading figure of the Danube School and among the first northern European painters to treat landscape as a subject in its own right, filling his pictures with towering trees, dramatic skies and tiny figures. Specialists say the new picture's fresh-to-market status, combined with its distinguished provenance, should make it one of the most closely watched lots of the winter season.

The sale will take place in Sotheby's Old Masters Evening Sale in London, where the Altdorfer will be offered alongside other early paintings. Its appearance is a reminder of how much important Renaissance art still sits unrecorded in private hands, waiting to be recognised.