Fool me once, shame on you; fool me twice, well, it must be April Fools' Day! Although no one is quite sure of the origins of this day, it has been celebrated for centuries in many different countries. Humour really does transcend borders! Over the years, there have been some truly memorable April Fools' Day jokes: in 1957, a BBC programme convinced its viewers that spaghetti was harvested from trees, while in 1985, Sports Illustrated readers were amazed to read about a pitcher who could throw a ball at 270 kilometres per hour.

Today's image shows a trompe l'oeil, or optical illusion, by French street artist JR on Palazzo Farnese in Rome. This trick of the eye makes it look like this Renaissance palace has been opened up, revealing the building's past.