Two treasure hunters who say research led them to the site in Poland where a Nazi train supposedly laden with unknown documents and valuables is buried in a tunnel have a new claim. The pair says the long-lost Amber Room stolen from the Russian czars could be on board the underground train near the Polish town of Walbrzych.

Reportedly valued at $385 million, or "priceless" to some, the Baroque-era Amber Room consisted of amber and gold leaf encrusted panels in a resplendent chamber considered to be the "Eighth Wonder of the World."

Ripped from the Catherine Palace near St. Petersburg in 1941, the Amber Room is perhaps the most extravagant lost art piece from the tens of billions of dollars worth of still-missing Nazi loot. (The room has since been recreated in the palace.)

Sleuthers Piotr Koper and Andreas Richter (a German national) say they want a reward for their discovery, but what they have found is not exactly known. Polish officials confirmed geo-radar imagery that supports the finding of an armored train, although the contents are not visible.

The excavation process has not yet begun due to safety concerns.