The legendary Amber Room was given by Frederick William I of Prussia to Russia's Peter the Great in 1716. During World War II, it was looted by the Nazis, who took the valuable amber to Königsberg, then in Germany. By the end of the war, the amber panels, which had been packed away in crates, disappeared. A replica can be seen in St. Petersburg, but the original remains missing to this day.

Historians deny that the so-called "Nazi gold train" ever existed, but that hasn't stopped treasure hunters from searching for it anyway. According to legend, the train carried valuable cargo — up to 300 tons of gold, paintings and other spoils of war — and was hidden by retreating Nazis in a sealed-up rail tunnel or mine somewhere in western Poland.

"The Song of the Nibelungs," an epic poem dating back to around 1200, is the first mention of the treasure. In the saga, the gold that Siegfried obtained in a battle against hundreds of warriors, 12 giants and a dwarf is dumped by Hagen von Tronje into the Rhine. But to this day no one knows exactly where. Some researchers believe that the gold was not sunk into the river, but buried.

In the year 70 CE, the Romans stole treasures from the Second Temple in Jerusalem: a golden candelabrum and the bejeweled Table of the Divine Presence, which was also made of pure gold. But with the fall of the Roman Empire they were lost. There are many theories about their whereabouts. Some believe the trove is kept in the Vatican, or that the gold was incorporated into the Kaaba, in Mecca.

Where is the last tsar's gold treasure? Maybe in the depths of Lake Baikal? According to legend, in the winter of 1920, two years after Tsar Nicholas II had been murdered, opponents of the new communist state tried to save wagons full of gold across the frozen lake. But they broke through the ice. The search for the treasure has been ongoing ever since.

In 1307, the wealthy Knights Templar became too powerful for the French King Philip IV. He had their leaders arrested and murdered. But where was their fortune? Philip's men did not find great wealth in the religious houses. Since then, the myth that the knights hid the treasure has persisted. Some treasure hunters believe it to be in Israel, Scotland or Oak Island in Canada.

The Japanese master blacksmith Okazaki Masamune (1264-1343) produced the legendary katana that the samurai Honjo Shigenaga is said to have carried. The long sword was a status symbol of the Tokugawa dynasty and was passed down from generation to generation for centuries — until it was stolen by the Americans after World War II in 1945. It hasn't resurfaced since.

This van Gogh painting, which shows the artist walking with his painting equipment in southern France, was stored with hundreds of other pictures in a salt mine in Stassfurt, south of Magdeburg, during World War II. Two fires in April 1945 are said to have destroyed the pictures. Or were they perhaps stolen by US soldiers or the Nazis? To this day, there is no trace of the painting.

In 2000, two of Darwin's notebooks disappeared after a photo shoot. Their value: several million pounds. Did the Cambridge University Library simply file them incorrectly? After two decades of unsuccessful searches, they unexpectedly reappeared in a publicly accessible area of the library in a pink gift bag, with an Easter greeting to the librarian.

There is no trace left of the 100-kilogram coin, which was probably melted down or chopped up and then sold. On March 27, 2017, the "Big Maple Leaf" coin was stolen from a display case in Berlin's Bode Museum and transported away with a wheelbarrow and skateboard. A spectacular theft. It was valued at €3.75 million. Several men from organized crime families were convicted in 2021.

This drawing by Carl Spitzweg was seized in 1939 from Jewish music publisher Heinri Hinrichsen, who was killed at the Auschwitz death camp in 1942. It was acquired by Nazi art dealer Hildebrand Gurlitt — and later found among the spectacular collection of works hoarded by his son, Cornelius Gurlitt. The work was auctioned by Christie's at the request of Hinrichsen's heirs.

The watercolor by the Jewish painter Max Beckmann entered Gurlitt's collection only in 1945. Held by the allied occupation forces at the Central Collecting Point in Wiesbaden from 1945-1950, it was returned to Hildebrand Gurlitt in 1950. Before working for the Nazi regime, Gurlitt had collected and exhibited modern art, curating Beckmann's last exhibition in 1936 before the artist fled Germany.

This work was owned by lawyer and art collector Fritz Salo Glaser. Artists of Dresden's avant-garde scene were his guests in the 1920s — as was the young Hildebrand Gurlitt. It is not known how Gurlitt came to possess the painting. It was confiscated in 1945 and later returned. Of Jewish heritage, Glaser only narrowly avoided deportation to the Theresienstadt concentration camp in 1945.

This painting by the famous impressionist is not suspected to have been looted. The artist sold it to the Durand Ruel Gallery in 1907. The Jewish art merchant and publisher Paul Cassirer is said to have given it to Marie Gurlitt as a present, and she left it to her son Hildebrand Gurlitt in 1923.

A short handwritten note allowed provenance researchers to identify this work by the French painter as a looted work of art. The picture was seized from the collection of Jewish politician and resistance leader Georges Mandel, who was executed by French fascists near Paris in 1944. German Culture Minister Monika Grütters (right) handed over the work to Mandel's heirs in January 2019.

The activist group Provenance Research Gurlitt identified this painting by French neo-impressionist Paul Signac as stolen Jewish property in October 2018. Gaston Prosper Levy fled Nazi-occupied France in 1940. Occupying soldiers are believed to have looted his art collection shortly before his escape. The painting was returned to Levy's family in 2019.

Hildebrand Gurlitt must have acquired this work by the French sculptor between 1940 and 1945. Previously belonging to the Frenchman Eugene Rudier, it entered circulation in 1919 at an auction by Octave Henri Marie Mirbeau, who is said to have received it as a present from the artist.

This copper engraving by Albrecht Dürer once belonged to the Falkeisen-Huber Gallery in Basel. It is not known how it got there or how long it was there however. In 2012 the engraving turned up in Cornelius Gurlitt's collection. "Old masters" like Dürer were very important to the National Socialists' view of art and were often exploited for propaganda.

The provenance of this drawing is completely unknown. It is certain, however, that Hitler considered Norwegian artist Edvard Munch's work "degenerate art." Some 82 pieces by Munch were confiscated in German museums in 1937.

Hitler venerated 18th-century French painting. He secured exceptional paintings for his own collection by targeting the collection of the Rothschild Family after the annexation of Austria. Hildebrand Gurlitt supplemented them with drawings by renowned French painters. He acquired this work by Boucher from a Parisian art merchant in 1942.

Cornelius Gurlitt hoarded the sculpture along with many other artworks for decades in his Munich apartment. Before his death in 2014, he consented to have his stocks researched and — should they include articles of stolen art — have them returned to their rightful owners in accordance with the Washington Principles on Nazi-looted art.