Once every minute, a camera takes an aerial picture of the public space in front of Barcelona’s cathedral. A simple algorithm converts the photograph into a vectorial register of the position of the people on the square. And that information is fed to a 3-axis robot equipped with a pen that simply draws it on a 50 cm by 70 cm paper canvas. A person is represented by a dot, labelled with a number and a short line going in the direction of the orientation of the sun at the moment at which the picture was taken. After completing the drawing of a photograph, the system finds the last picture taken and undertakes the drawing of a new set of lines on the same canvas. It repeats the action form 10 am to 8 pm, overlapping the lines of hundreds of photographs, of thousands of people. Every day a drawing gets started on a fresh white page.