The Private Life of an Easter Masterpiece. Six hundred years ago, one painting in northern Europe was prized above all others. Queens and kings wanted to own it. Other and lesser painters endlessly copied it. Anyone who saw it was struck with awe. The painting was huge and overwhelming - the Descent from the Cross. The painter was a Flemish master, Rogier Van Der Weyden. Today it is one of the greatest masterpieces in Spain's National Gallery, the Prado, in Madrid. It was taken there by Philip II of Spain and survived great adventures - almost lost at sea, almost destroyed by German bombers in the Spanish Civil War. Recently Google Earth went inside a gallery for the first time - they chose the Prado and then the Descent from the Cross. Only today can the highest resolution digital cameras capture the amazing attention to detail of Van Der Weyden's paintbrush.

• Samuel West