"A hidden message in a painting has led to the first evidence of a 'lost' Leonardo da Vinci masterpiece that has lain hidden for 400 years in a secret compartment behind another mural in Florence, scientists announced today.
An 'endoscopic' probe was inserted into the interior of the wall in the Palazzo Vechio, and obtained chemical samples of a dark pigment which Da Vinci also used in the Mona Lisa." —MailOnline
From Josef von Sternberg's The Scarlet Empress (1934); featuring Sam Jaffe and Marlene Dietrich; cinematography by Bert Blennon; art direction/department: Hans Dreier, Peter Ballbusch, and Richard Kollorsz.