The Nazis plundered an estimated 20% of European art from Jewish collectors and other individuals and organisations in occupied countries. To this day, hundreds of thousands of artworks, which include Old Master paintings and the exquisite 'Eighth Wonder of the World', have never been recovered. Click or scroll through as we look at 10 of the most important treasures that are still missing.

This masterpiece by Van Gogh features on the Monuments Men Foundation's most wanted list. The foundation was set up in 2007 in memory of the men and women of the Monuments, Fine Arts, and Archives programme, who recovered countless works of art stolen during World War II and whose story was told in the 2014 film The Monuments Men.

The self-portrait, which was painted in 1888 and hung in the Kaiser-Friedrich Museum in Magdeburg, Germany, was taken by the Nazis in the early part of World War II and hidden in their secret salt mines art repository in Stassfurt. While some reports suggest it was destroyed by fire, other sources indicate the artwork survived and might be out there somewhere.

During the early part of the 20th century, Dutch banker and collector Friedrich Gutmann amassed one of Europe's most impressive private collections of art, which included this portrait by German Renaissance artist Cranach the Elder, which went missing in World War II.

In 1939, Gutmann sent the bulk of his collection abroad for safekeeping but kept a number of artworks at his mansion in Heemsteed. A Christian convert with Jewish ancestry, Gutmann was forced by the Nazis to sell what remained of his collection. In 1943, he was deported, along with his wife, to Theresienstadt concentration camp, where he was brutally murdered the following year.

Another priceless painting that appears on the Monuments Men Foundation's most wanted list, this portrait by Early Renaissance painter Sandro Botticelli was the most treasured object in the Filangieri Museum in Naples, Italy, until the Nazis got their hands on it.

On 30 September 1943, Nazi troops discovered the painting in a villa in Naples, where it was being hidden and, as they did with so many exceptional works of art, wasted no time stealing it. The portrait vanished en route to Germany and its whereabouts remain unknown.

A failed artist who fancied himself as a critic and collector, Hitler was planning to create the Führermuseum, a major art gallery in Linz, Austria, which would have displayed the most important treasures stolen by the Third Reich (the picture shows the House of German Art, which he did have built in Munich). Among the artworks earmarked for the gallery was An Angel with Titus' Features by Rembrandt.

The painting, which features the Dutch Master's son, was stolen by the Nazis from a chateau in rural France in 1943 and ended up in a Paris warehouse, awaiting the building of the Führermuseum, which never happened. After that, the trail runs cold and the painting is presumed destroyed, or might very well be languishing in a clandestine collection somewhere.

Jewish banker and collector Hans Rudolf Fürstenberg bought this sculpture from the renowned artist Auguste Rodin sometime in the early part of the 20th century. Fürstenberg fled Germany for France in 1937, and the sculpture was eventually stolen by the Nazi looting agency, Einsatzstab Reichsleiter (ERR).

The sculpture was stored in a Paris warehouse for a time, but went astray around 1942, and is considered lost forever. Fortunately, Fürstenberg survived the war, having sought refuge in neutral Switzerland. Despite his best efforts, the avid art enthusiast was unable to recover a significant part of his collection.

Not all the artworks seized were admired by the Nazis. In fact, art that was deemed 'degenerate' by the Third Reich was looted and either destroyed or sold on. This included many modern works of art such as Jean Metzinger's En Canot.

The hugely influential Cubist painting, which caused a sensation when it was exhibited in Paris in 1913, was eventually acquired by Berlin's National Gallery. The Nazis confiscated the painting in 1936 and it featured in Hitler's Degenerate Art Exhibition in Munich. Since then, En Canot has been missing, likely destroyed.

Unlike the paintings and sculptures of many of his contemporaries, Gustav Klimt's artwork was never labelled 'degenerate' by the Nazi authorities. Still, a number of the Austrian symbolist's canvases were seized by the Third Reich, including the Portrait of Trude Steiner, which was painted in 1900.

The portrait depicts the daughter of Jewish collector Jenny Steiner, who fled Austria in 1938. The artwork was confiscated by the Nazis following Steiner's lucky escape and sold to a mysterious buyer in 1941. The painting hasn't been seen since, and whether it survived the war is anyone's guess.

A seminal piece by the great Renaissance artist Michelangelo, the Head of a Faun was the Old Master's first known marble sculpture, and the artwork that won him the patronage of the powerful Florentine leader Lorenzo de' Medici. 

The sculpture, which is the property of the Bargello Museum in Florence, Italy (pictured), was looted in August 1944 by Nazi troops and loaded onto a truck, along with other priceless artworks. Some experts have suggested the sculpture may have eventually found its way to the Soviet Union, but Michelangelo's first marble artwork remains lost to this day.

This 1513/14 artwork by the quintessential painter of the High Renaissance is regarded as the most important painting missing since World War II. Raphael's Portrait of a Young Man was stolen from the aristocratic Czartoryski family in Kraków, Poland in 1939.

The painting, which had been squirrelled away by Prince Augustyn Józef Czartoryski, was discovered by Gestapo agents working for Hans Frank (pictured), the Nazi Governor-General of Poland. The portrait ended up in Frank's villa in Neuhas, Germany, but its whereabouts have been unknown since 1945.

The star attraction of the Catherine Palace in St Petersburg, the gold and amber-laden Amber Room (the reproduction version is pictured) was widely regarded as the 'Eighth Wonder of the World'. Created in the early 18th century for Frederick, King of Prussia, the gilded masterpiece was stolen by the Nazis during Operation Barbarossa in 1941.

The curators of the palace had tried to hide the room by covering it in wallpaper but to no avail, and the masterpiece was taken by the Nazis to Königsberg Castle in Kaliningrad, which was then part of Prussia. The priceless room is thought to have been destroyed along with the castle in 1945, while some experts believe it was saved and may be stashed away somewhere in Poland. Three German treasure hunters claimed in 2017 that they had found it hidden in a cave in eastern Germany. More recently, divers are to search the wreck of a German ship, the Karlsruhe, sunk off the coast of Poland in 1945, after "non-military crates" were spotted among the wreckage.

Now read about the treasures the Nazis stole that were sensationally recovered