Leonardo da Vinci was born on April 15, 1452, in a small town near Florence, Italy. He became one of the greatest painters who ever lived. His most famous work, the Mona Lisa, hangs in the Louvre Museum in Paris. Over ten million people visit it every year. The painting shows a woman with a mysterious smile. Some people think she looks happy. Others think she looks sad. Scientists have studied the painting and found that Leonardo used a technique called sfumato. This means he blended colors so smoothly that there are no sharp edges. The corners of the Mona Lisa's mouth are slightly blurred. This is why her expression seems to change depending on where you look. Leonardo also painted The Last Supper on a wall in a church in Milan. It shows Jesus and his twelve disciples at dinner. Leonardo arranged the figures so that every face shows a different emotion. Some look shocked. Some look angry. Some look confused. Leonardo worked very slowly. He sometimes stared at a painting for hours before adding a single brushstroke. Leonardo told a monk that painters work hardest when they appear to be doing nothing.