The Amber Room is probably still on that train that is hidden in an old German tunnel. /jk
[snip] As the forces moved into Pushkin, officials and curators of the Catherine Palace attempted to disassemble and hide the Amber Room. When the dry amber began to crumble, the officials instead tried hiding the room behind thin wallpaper. But the ruse didn’t fool the German soldiers, who tore down the Amber Room within 36 hours, packed it up in 27 crates and shipped it to Königsberg, Germany (present-day Kaliningrad). The room was reinstalled in Königsberg’s castle museum on the Baltic Coast.
The museum’s director, Alfred Rohde, was an amber aficionado and studied the room’s panel history while it was on display for the next two years. In late 1943, with the end of the war in sight, Rohde was advised to dismantle the Amber Room and crate it away. In August of the following year, allied bombing raids destroyed the city and turned the castle museum into ruins. And with that, the trail of the Amber Room was lost. [/snip]
https://www.smithsonianmag.com/history/a-brief-history-of-the-amber-room-160940121/