Rare Renaissance masterpiece hidden for 70 years could fetch £5m at auction

Exclusive: Experts say Albrecht Altdorfer’s 1520 landscape is ‘one of the most exciting discoveries imaginable’

An exceptionally rare painting, described as one of the earliest landscapes in western art, goes on auction in London next month.

It was completed around 1520 by Albrecht Altdorfer, who is widely regarded as Europe’s first pure landscape oil artist.

The Renaissance artwork – A Thickly Wooded Landscape With a Rainbow Behind the Trees and a Distant Outcrop to the Right Beneath a Cloud-Laden Sky – has not been seen in public for 70 years because it was held in a private Swiss collection.

It will go under the hammer at Sotheby’s on 9 December for an estimated £3m to £5m – the first time a known work by the artist has come up for…