In July, Sotheby’s will offer for sale one of the greatest works by J.M.W. Turner still held in private hands. Painted in 1835, 'Ehrenbreitstein' dates from a period that is widely considered Turner's best. Though he made many drawings and watercolours of German views, this painting of the ruined fortress of Ehrenbreitstein, near Coblentz, is thought to be the most important oil painting of a German subject ever painted by the artist. 'Ehrenbreitstein' will be offered as a major highlight of Sotheby’s Old Masters Evening sale on Sotheby’s in London on 5 July.