Finders keepers.

These amber panels, backed with gold leaf and mirrors, once dressed an entire chamber in the Catherine Palace near Saint Petersburg. More than a decade in the making, they covered 55 square meters and contained more than six metric tons of amber. Some called them the eighth wonder of the world.

The Nazis took them during World War II, but after that they disappeared. Postwar rumors have put them in bunkers, in mines, in submarines, in lagoons. One stone mosaic turned up in 1997 in West Germany, and its fellows were found in Königsberg Castle, where the Nazis had secreted them. But the rest of the “Amber Room” has simply disappeared — lost in a fire, still hidden, or safe in the hands of a lucky, and quiet, treasure hunter.

On Nov. 14, 2002, this image was discovered during restoration of a church’s exterior wall in Malta, Austria. It’s part of a 14th-century fresco depicting Saint Christopher, who is often shown accompanied by fabulous creatures.

Draw your own conclusions.

Besieged by Prussians in 1870, Paris found a clever way to get mail to the outside world. For 20 centimes you could write a letter on a thin piece of green paper; these were collected and sent hopefully upward on unguided mail balloons. Each 4-gram postcard carried an address; the Parisians hoped that the balloons would drift to earth somewhere and that whoever found the messages would forward them.

It worked. During the four-month siege they sent up 65 balloons, and only two went missing.

If Ebenezer Scrooge were a woman, he’d look like this. Hetty Green (1834-1916) amassed more than $100 million as a shrewd businesswoman, but today she’s remembered mostly for her breathtaking stinginess.

Born into a Massachusetts whaling family, Hetty was reading financial papers to her father at age 6 and keeping the family books at 13. She inherited $7.5 million on her father’s death, and reportedly married only to keep her relatives at bay (she made her fiance sign a prenup). When her husband divorced her and then died, she moved to Hoboken and basically went nuts.

Legends say she never heated her house or used hot water; that she wore one old black dress; that she rode in an old carriage. Rather than pay rent, she sat on the floor of New York’s Seaboard National Bank and ate only oatmeal heated on the office radiator, and she would travel thousands of miles to collect a debt of a few hundred dollars.

Almost no expense was worthwhile. Her son’s leg had to be amputated when she tried to treat him at home. She herself refused treatment for a hernia because it cost $150.

When she died, at age 80, she may have been the richest woman in the world. Unfortunately, you can’t take it with you.