The final crates were hauled from the salt mine at Altaussee in the summer of 1945, their canvas surfaces still cool from the mountain’s embrace. The explosives that had been wired among them, primed to erase a millennium of European culture, had been quietly defused by Austrian miners who risked execution to save their livelihood and their heritage. The art survived by days.

But the survival of the objects was never the end of the story. It was the beginning of an accounting that, eight decades later, remains bitterly unfinished.

The theft was not a byproduct of war’s chaos. It was a bureaucratic enterprise, staffed, cataloged, and executed with the precision of a government ministry. In July 1940, weeks after the fall of France, Adolf Hitler authorized a special task force to systematically comb occupied Europe for art worth taking.

Named for the Nazi ideologist Alfred Rosenberg, the Einsatzstab Reichsleiter Rosenberg—the ERR—became the largest art looting operation in history. Its mandate was simple: strip the continent of its cultural treasures, and do it legally, efficiently, and without mercy.

In Paris, the ERR established its headquarters inside the Jeu de Paume, a small museum adjacent to the Tuileries Gardens. Between late 1940 and the summer of 1944, more than 20,000 looted works passed through its rooms. Most came from Jewish families and dealers who had fled or been arrested, their collections stripped from walls and vaults in a single night.

The Rothschilds. Paul Rosenberg. The great dealers of the Marais.

Their paintings were laid out on tables, photographed, cataloged, and crated for shipment east into the Reich. Two men decided where the best of it went.

Hitler intended the finest works for a vast museum he planned to build in Linz, the Austrian city of his youth, a monument meant to rival Vienna and Paris. He tracked his future collection from a distance in leather-bound albums of photographs, each page showing a painting marked down for Linz. Hermann Göring, the second most powerful man in the Reich, built a collection of his own.

He visited the Jeu de Paume roughly twenty times in person, selecting pieces for his country estate at Carinhall. By the war’s end, he had amassed roughly 1,500 works, many of them stolen. The competition between the two men was personal, obsessive, and utterly devoid of moral constraint.

Not everything the regime took was meant to be kept. Years earlier, the Nazis had stripped German museums of modern art they branded degenerate—works by Picasso, Matisse, and the German expressionists. A handful of approved dealers were allowed to sell those abroad for foreign currency the Reich desperately needed.

The same machine that hoarded old masters quietly sold off the modern ones. The looting spread across the whole of occupied Europe. In grand houses across Paris, families came home to pale rectangles on the walls where paintings had hung for generations.

From the Netherlands came Dutch masters bought up cheaply or seized through forced sales. From Italy came Renaissance paintings and sculpture. From Poland came entire museum and church collections, crated into trucks and loaded onto trains in the first weeks of the occupation, before the country had even stopped burning.

By 1945, the regime had taken hundreds of thousands of objects from across the continent. As Allied armies closed in, the Nazis hid the hoard wherever they could—in castles, monasteries, and above all in mines where the steady temperature protected the canvases. The largest of those hiding places was at Altaussee in the Austrian Alps.

More than 6,000 paintings were stored in the tunnels, gathered for Hitler’s Linz Museum, along with sculptures, drawings, Michelangelo’s marble Madonna from Bruges, and the Ghent Altarpiece. As the Allies advanced, local Nazi officials ordered the mine destroyed. Crates of explosives were carried inside.

Austrian miners, unwilling to see the mine and their livelihood blown apart, secretly removed the bombs.

The job of finding it fell to an unlikely unit. The Monuments, Fine Arts, and Archives section—later known as the Monuments Men—was a small group of curators, art historians, architects, and archivists in Allied uniform. Their task was to protect Europe’s cultural treasures during the fighting and to track down what the Nazis had stolen.

Fewer than 400 served across the whole war, drawn from more than a dozen nations. At first, they had almost no vehicles, no staff, and little authority. In April 1945, American troops uncovered a salt mine at Merkers in Central Germany.

Inside lay much of the German gold reserve and a trove of paintings pulled from Berlin’s museums. General Eisenhower came down to the mine to see it for himself. It was a stunning find, but it was not the largest.

When two Monuments officers, Robert Posey and Lincoln Kirstein, reached the tunnels at Altaussee in May 1945, they found the art intact, stacked on wooden racks in the cold, dry air. The conservator George Stout then spent weeks carefully bringing each piece back up to the surface. Recovering it was not the problem.

Knowing who it belonged to was another. Here, the work of one woman proved decisive. Rose Valland had stayed on at the Jeu de Paume throughout the occupation, quietly watching the Germans sort their loot.

Without their knowledge, she wrote down what came in, where it was sent, and which trains carried it away. Her notes later helped Allied teams trace tens of thousands of works back to their owners.

The recovered art was carried to collecting points the Allies set up across Germany, the largest at Munich and Wiesbaden. There, it was unpacked, inventoried, photographed, and sorted by country. Then the long task began.

The Allies returned the works to national governments first, and left those governments to find the individual families. It was a reasonable system on paper. In practice, it would leave thousands of pieces stranded for the rest of the century.

Most of the art the Allies recovered went home. Whole national collections from France, the Netherlands, Italy, and Poland were handed back to their governments within a few years. But returning a painting to a country was not the same as returning it to a person.

Many of the original owners had not survived the war, and their heirs were scattered, or could not be traced at all. Works with no claimant were absorbed into state collections, where some quietly remain.

Not everyone agreed on how the recovered art should be handled. In November 1945, the US Army ordered 202 German-owned paintings shipped to the United States for safekeeping. More than 20 Monuments officers objected in writing, led by Walter Farmer, who ran the Wiesbaden collecting point.

They argued that removing a nation’s cultural property, even a defeated enemy’s, was exactly what they had spent the war trying to prevent. Their protest became known as the Wiesbaden Manifesto. The paintings were eventually sent back to Germany.

Other art went east and did not come back. As the Red Army pushed into Germany, Soviet trophy brigades followed the troops, collecting paintings, sculpture, and whole museum holdings to carry home as payment for the destruction the Soviet Union had suffered. Some works were returned in the 1950s.

Many were not.

One of the most famous was Priam’s Treasure, the hoard of Trojan gold once dug up by Heinrich Schliemann. Taken from Berlin in 1945, it vanished for half a century until the Pushkin Museum in Moscow finally admitted in 1994 that it had had the gold all along. For years, the Soviet Union denied holding any of it.

Only after the Cold War ended did Russian museums begin to admit how much trophy art sat in their storerooms. Then in 1998, Russia passed a law that declared the works state property and compensation for wartime losses, which made returning them all but impossible. Much of what the Red Army carried east in 1945 is still there today, behind glass in Moscow and St.

Petersburg.

A few treasures simply disappeared. The Amber Room, a chamber of carved amber panels taken from a palace near Leningrad, was lost in the final months of the war and has never been found. So has Raphael’s Portrait of a Young Man, seized from a museum in Krakow in 1939.

Often called the most important painting still missing from the war, it has not been seen since. For decades after the war, the search slowed. The collecting points closed in the early 1950s.

The Monuments Men went home, and the unclaimed works settled into museums and private collections around the world. Many stayed there for two generations, their histories quietly forgotten, hanging on gallery walls with no mention of how they’d been acquired.

Then the question came back. In December 1998, representatives of 44 countries met in Washington and agreed a set of principles on Nazi confiscated art. They called on museums and governments to research the history of the works in their care and to find just and fair solutions with the families they’d been taken from.

The agreement carried no force of law, but it reopened thousands of cases that everyone had assumed were closed. One of them became famous. Maria Altmann, an Austrian-born refugee living in California, spent years fighting to recover five paintings by Gustav Klimt that had belonged to her family before the Nazis seized them in Vienna.

Among them was the golden portrait of her aunt, Adele Bloch-Bauer. For Maria, the fight was never only about value. The portrait was one of the last links to a family the war had scattered, and winning it back meant forcing Austria to admit, after more than 60 years, how it had been taken.

In 2006, an arbitration panel in Austria ruled in her favor, and the paintings left the national gallery for a private heir. The portrait was later sold for $135 million, at the time one of the highest prices ever paid for a painting.

Some discoveries came by accident. In 2012, German tax investigators searching a Munich apartment found more than a thousand works stacked among the belongings of an elderly recluse named Cornelius Gurlitt. His father had been one of the dealers the Nazis used to handle looted and confiscated art.

Among the hoard were pieces by Picasso, Matisse, and Chagall that had not been seen in public for 70 years. When the find was made public in 2013, it caused an international sensation. Gurlitt died the next year and left the entire collection to a museum in Switzerland, which agreed to keep researching and return anything proven to be looted.

The Gurlitt case was a reminder that the story is not history yet. A painting still surfaces at auction with an empty gap in its record covering the war years, and a researcher starts pulling the thread. A family receives a letter telling them a work their grandparents once owned has been found in a museum on another continent.

More than 80 years after the war, the accounting is still unfinished. Some paintings came home. Some hang in museums today under new labels.

Some vanished into private rooms, bank vaults, and museum storerooms in the East. Provenance researchers still work the gap, matching a name on a wartime list to a canvas on a gallery wall. And somewhere, perhaps a missing masterpiece hangs in plain sight, seen every day by people who have no idea where it came from.

The explosives were removed from the mine, but the charge they represented—the moral and legal obligation to return what was taken—has never been fully defused.