Charles Edward Stuart, colloquially referred to as Bonnie Prince Charlie, fomented the Jacobite uprising of 1745 in an effort to seize the British throne. Charlie's Scottish troops were defeated in battle a year later and he fled to France. In the brutal English crackdown that ensued, Scottish households found to contain a portrait of Bonnie Prince Charlie were in for trouble, so former supporters interested in surviving got rid of them.
But not all of them. One artist used a clever technique to secretly hide a portrait of BPC in plain sight. A seemingly abstract circular pattern was painted on a tray...
...and once a mirrored cylinder was placed in the center, boom, you had Bonnie Prince Charlie staring back at you.
The tray and cylinder are on display at the West Highland Museum in Scotland. Sadly, the artist who created the work will remain anonymous in perpetuity. "The artist is unknown," the museum writes, "and there is no record of the portrait's owners. It was discovered by chance in a London shop by the founders of the Museum and is one of our best known exhibits."
The painting technique is called anamorphosis, and there are artists still creating anamorphic cylinders. Here's a modern-day version created for the Inverness Museum: