Art treasures taken by a Soviet officer from a castle in Nazi Germany went on display in Moscow on Saturday, despite a political row.
A campaign by mainly Communist members of Russia's parliament has kept the 364 works in the country, though many Liberals back the idea of returning them to Germany.
Returning war booty has long been a sensitive issue in Russia, where memories remain keen of more than 20 million Soviet war dead during a four-year campaign against the Nazis.
The Moscow Museum of Architecture has held the 362 drawings and two paintings - which include works by Rubens, Degas, Delacroix and Goya - in safekeeping for 43 years.
Viktor Baldin, an architect by profession, came across the artworks in the cellar of a castle where they were being plundered by Red Army soldiers.
He immediately realised their value, engineered swaps with the soldiers and packed them for transport.
Back in Moscow, Baldin kept them under his bed for two years before handing them to the Architecture Museum, which he later headed.
As museum guardians we don't want to start any fights
David Sarkisyan, Moscow Museum of Architecture
Baldin's widow, who said her late husband had long campaigned for the works to be returned to Germany, was at Saturday's opening.
Yulia Baldin, 77, said the works would be handed back ultimately. Opponents, she said, should "calm down."
"Common sense will prevail," she said.
Museum director David Sarkisyan said it was "sad" that the works had caused a "political scandal and an atmosphere of controversy".
"As museum guardians, we don't want to start any fights," he added.
"The war is over in all areas. We befriend Germans, we marry Germans, both sides dream of making trips here or there.
"But, for some reason, a war is proceeding in terms of culture."
Culture Minister Mikhail Shvydkoi is currently heading a campaign for the works to be returned. Liberals back the idea as a gesture of friendship to Germany, Moscow's biggest trading partner.
Shvydkoi says the collection is quite different from artwork seized on the orders of the Soviet high command.
But former Culture Minister Nikolai Gubenko, now a Communist member of parliament, says the paintings are Russian property.
The collection is valued at $23.4m (£14.9m), with a Goya painting the most valuable at $4.6m (£2.9m).