According to Polish lore, a Nazi train loaded with gold, artworks and weapons vanished into a mountain at the end of World War II, as the Germans fled the Soviet advance. Now two men claim they know the location of the mystery train and are demanding 10 percent of its value in exchange for revealing its location. Historians say the existence of the train has never been conclusively proven, but authorities are not passing up this chance at possibly recovering treasures that locals and the government have sought for 70 years. “We believe that a train has been found. We are taking this information seriously,” Marika Tokarska, an official in the southwestern Polish district of Walbrzych, told The Associated Press on Thursday.