31. The Amber Room, Russia

The Amber Room was a chamber of gold and amber, decorated with mirrors and gold leaf. A striking, ornate room, it was originally built within the Berlin City Palace in 1707. It was eventually moved to the Catherine Palace when Prussian King Frederick William I gifted it to his ally Tsar Peter the Great of the Russian Empire in 1716.

It was a priceless piece of art, and with art comes art thieves. The Amber Room was looted by Nazi soldiers during World War II. Where it went after that, no one is quite sure as it mysteriously vanished after the war and was never seen again. What a mystery!