'Art is the queen of all sciences communicating knowledge to all the generations of the world.' Let’s ponder these inspirational words by Leonardo da Vinci on World Art Day, April 15, which was also the birthday of the renowned Renaissance artist. From his iconic painting of the Mona Lisa to his detailed sketches of flying machines, Leonardo pushed the boundaries of knowledge and talent in a wide range of fields. Today's homepage shows the RedBall Project at Centraal Station in Antwerp, Belgium. Created by the American artist Kurt Perschke, this traveling public art installation is considered to be the world's longest-running street artwork. Since 2001, the 15-foot inflated red ball has been wedged into dozens of landmarks in countries from Australia to England.