There are hundreds of thousands of treasures around the world stolen by the Nazis before and during World War II from Jewish families and art dealers. While many are missing, the locations of others are well known but the current owners are proving reluctant to part with them. Here are 10 cases of looted art where the owners are demanding its return – or, in at least one case, where the owner is being sought.

Germany and the Prussian Cultural Foundation (SPK) appealed, but ultimately lost, a US court decision to allow the heirs of the Jewish art dealers who sold the trove of 42 pieces of ecclesiastical art, now worth over $250 million (£190m), to sue for their return. A US court accepting a Nazi loot case is unprecedented and could mean the burden of proof shifts from heirs to museums to show rightful ownership of art, books and other treasures acquired in Nazi times.

In 1929 Prussian aristocrat the Duke of Brunswick sold the Guelph reliquaries off, and part of the collection went to a consortium of four Jewish art dealers – the ancestors of the plaintiffs. The dealers, in turn, sold a chunk of the artefacts for 4.25 million Reichsmarks to the Prussian state in 1935, then governed by infamous Nazi Hermann Goering and presented by him to Adolf Hitler as a personal gift. The plaintiffs say that the sale constituted a 10% loss and was made under duress.

In 2008, attorneys representing heirs Jed Leiber, Gerald Stiebel and Alan Philipp requested the return of the treasure from the state-funded Prussian Cultural Foundation. In 2015, the German Limbach Commission recommended it be left in Berlin, where it is on display at the Museum of Decorative Arts. But the heirs filed a US lawsuit and, in 2017, a federal judge ruled that the Prussian Cultural Foundation could be sued in America. It was appealed, but the decision was upheld last summer.

Last November American Bruce Berg, also filed suit in the US to recover 143 paintings from the Netherlands now worth tens of millions of dollars, including this Roman Landscape by Guilliam van Nieulandt. Berg’s grandfather and great-uncle, Benjamin and Nathan Katz, were Dutch Jewish gallery owners, and Berg claims the paintings were sold to the Nazis under threat of deportation to concentration camps.

After World War II, Benjamin Katz filed claims to have more than 140 works returned to him. Rembrandt’s Portrait of Dirck Jansz Pesser was one of 28 returned, believed to have been traded to the Nazis for 25 exit visas for Katz family members to escape. It now hangs in the Los Angeles County Museum. After the war, Benjamin had returned to the Netherlands, where he was investigated by the government as a Nazi collaborator, but never prosecuted. His brother opened an art gallery in Switzerland.

Three generations of Berg’s family have tried to regain other works over the years, including pieces by Jan Steen and Philip van Dijk, which are said to be in museums including the Centraal Museum in Utrecht, the Rijksmuseum in Amsterdam and the Dordrechts Museum in Dordrecht. In 2013 the Katz heirs had one further success when the Dutch Restitution Committee ordered Ferdinand Bol’s Man With A High Cap to be returned to them from the Museum Gouda, although it rejected the rest of the claim.

A pair of 17th century salt cellars by Johannes Lutma was flagged by the Rijksmuseum in Amsterdam a few months ago as having “problematic provenance”, according to the Dutch Museums Association. It says they appear to have been part of the estate of Emma Budge confiscated by the Nazis in 1937. In a long investigation into looted art in the country’s museums, concluded at the end of 2018, the Association has discovered at least 170 artworks stolen by Nazis.

Emma Budge was a wealthy Jewish art collector, whose collection was auctioned off in 1937 after her death, as per her will. But her beneficiaries never received the proceeds, with many fleeing the country. The Budge family has made cases for more than 200 pieces, and has received about 25 back. One it lost out on was a $355,450 (£270k), 18th century Meissen porcelain figure of Pulcinell, sent to a private Japanese buyer from the UK last year, despite a spoiliation claim from the Budge family.

In 2017 German frozen pizza firm Dr Oetker compensated the Budge family for a silver windmill cup in its vast private art collection. It acquired the cup in 2009 and contacted the family’s lawyers after a voluntary audit of its own collection matched the cup with an image on an online registry for Nazi-looted art . Former billionaire boss Rudolf August Oetker was a member of the Waffen SS, who provided pudding mixes to Nazi troops.

Since 2010 the family of Baron Mór Lipót Herzog have been trying to sue the Hungarian government, three museums and a university in the US for the return of 40 pieces they claim has a combined value of over $100 million ($76m), including The Agony in the Garden of Gethsemane by El Greco, pictured.

But in early 2019, the US Supreme Court upheld a ruling that US courts lack jurisdiction over the Hungarian state. The family are still pursuing a case against the Hungarian Museum of Fine Arts, the Hungarian National Gallery, the Museum of Applied Arts and the Budapest Technological University to restitute pieces such as The Annunciation to Saint Joachim by Lucas Cranach the Elder, pictured.

The Baron had amassed some 2,500 paintings, but after his death in 1934, the collection was seized by wartime German ally Hungary in a mass confiscation of Jewish-owned art. Although a portion was returned to the family on loan, they claim they were forced by “relentless harassment” to give the works to the Museum of Fine Arts in Budapest, pictured.

Another case to be heard in the US courts is against Spain over a Camille Pissarro painting, Rue Saint-Honoré in the afternoon, effect of rain, valued at around $30 million (£23m). Lilly Cassirer Neubauer, whose Jewish family owned an art gallery in Germany, inherited the painting in 1926 and displayed it in her living room until 1939, when she was forced to sell it for $360 (£273) in exchange for safe passage out of Germany.

The Cassirers believed the painting to be lost, until a friend spotted it at the Thyssen-Bornemisza museum in 2000. Lilly’s heir, Claude Cassirer, sued in 2005 to have it returned. The Pissarro had ended up in the hands of German industrialist Baron Hans Heinrich Thyssen-Bornemisza, who sold his collection to Spain in 1993 for $350 million (£266m). A court awarded the painting to Spain, though the Cassirer heirs have appealed this ruling. A Los Angeles federal court is now deciding the case.

The Cassirers claim the baron, a major art collector, would have noticed many “red flags” about the painting indicating it was probably stolen, such as the remnants of a sticker from the Cassirer family art gallery on the back of the painting which would suggest it had been in Berlin. The Madrid museum insists it acquired the work in good faith, as did the baron, and is “convinced of the legitimacy of its ownership”, according to the foundation that owns it.

The family of Jewish art collector Emmanuel Lewenstein are taking their case to court after a Dutch restitutions committee decided late last year to allow Amsterdam’s Stedelijk Museum to hold on to the looted Kandinsky artwork Painting with Houses, pictured.

The Stedelijk (pictured) bought the painting at auction in 1940, a sale that the descendants of Emmanuel Lewenstein claim was made under duress five months after Germany invaded the country and was bought for a “modest sum”. They made their claim in 2013 but the committee ruled last year that the family had been in financial difficulties at the time of the auction and did not try to claim it back after the war.

However the restitution committee has also come under fire for acknowledging its decision also took into account the need to maintain the country’s “public art stock”. The Lewenstein family’s lawyer called the decision “unacceptable” and said the works in question would not have been sold had the war not taken place. A writ has been served on the Municipality of Amsterdam and the Stedelijk Museum to appear at the Amsterdam District Court.

In another case raised by the Lewenstein family for another Kandinsky, the $85.5 million (£65m) artwork Colourful Life or Das Bunte Leben is the subject of a lawsuit against the bank Bayerische Landesbank.

The heirs claim the painting was loaned to the Stedelijk Museum for safekeeping before the war, but then sold at auction in 1940 without their permission and at a greatly reduced price of 250 Dutch Guilders, which would only have been 10-20% of its value. The family say they received no proceeds.

The heirs filed their suit against the bank in 2017. The painting is hanging in the Lenbachhaus gallery in Munich, Germany, where it has been on loan from the bank for 40 years. The bank says it legally acquired the painting but is “willing” to take part in a review, although it hopes the painting will remain on public display at the Lenbachhaus.

In another case involving a Pissarro, a Paris appeals court in October upheld a ruling ordering an American couple to return the painting Picking Peas or La Cueillette to the descendants of Jewish businessman Simon Bauer, from whom it was seized in 1943. The couple, Bruce and Robbi Toll, who are also Jewish, had loaned Picking Peas to the Marmottan Monet museum (pictured) for a Pissarro retrospective in 2017, where one of Bauer’s heirs spotted it.

The Tolls appealed after the ruling, saying they bought the painting for $800,000 (£608k)in 1995 in good faith, but the decision was upheld. It has not been reported whether the transfer of the painting – held in escrow by the Musée d'Orsay and Orangerie museums (pictured) – has taken place yet. The Bauers’ lawyer said his clients now hope the Tolls will “respect the decision of the Paris Court of Appeal and not to keep going with the procedures which only aggravate the harm they have suffered.”

The Pissarro, insured by the Tools for $1.75 million (£1.3m), is said to have originally been bought by Theo van Gogh, the brother of Vincent van Gogh, who purchased it from Pissarro. The Bauer family previously received €109,304 euros ($125k/£95k) in compensation for its loss and their lawyer says they will return that money once they have the painting back.

Like the Lutma salt cellars, the provenance of this 15th century painting of The Lamentation of Christ by Hans Memling (pictured) has been found to be potentially contaminated in the investigation by the Dutch Museums Association concluded late last year. It is in storage at the Museum Boijmans Van Beuningen in Rotterdam.

The museum (pictured) says the painting was owned by Jewish art dealer Arthur Goldschmidt in 1936. The museum says his name is “associated with the trade in spoiliated art”. Goldschmidt fled Germany and settled in Paris, but was jailed and his collection seized when Paris was occupied by the Germans in 1940. The museum says it is unknown from whom and when Goldschmidt acquired the painting. It was bought in 1936 by DG van Beuningen and went to the museum as part of his collection in 1958.

Another of the 170 pieces the project has found to be stolen is Salome with the Head of John the Baptist by Jan Adam Kruseman (pictured), which is in the Rijksmuseum. A spokesman for the project said the research was important to “do justice to history”. However, often the trail will have died along with the original owners – who may have been murdered by the Nazis – or because there is no proof of ownership of the work.

This piece of art is not hiding in plain sight. However, a replica of it is, in a Florence art gallery’s hopes of shaming its current owners into handing it over. The Jan van Huysum painting, Vase of Flowers, was first displayed in Florence in 1824 after Grande Duke Leopoldo II bought it for his art collection. However, it was stolen by German troops in 1944 as they retreated north.

Uffizi Gallery head Eike Schmidt, a German himself, said the German government had a "moral duty" to help bring Vase of Flowers, which is held by a German family, back to the museum. Until it is, a black and white photo of the still life will hang in the gallery, stamped with the word “stolen” in English, German and Italian.

However, Lawyers for the unidentified family have demanded payment, and Germany says a statute of limitations on crimes committed more than 30 years ago means it is helpless to intervene.