Mona Lisa, 1517 by Leonardo da Vinci 

Leonardo da Vinci's "Mona Lisa" is a renowned portrait of a woman with a mysterious expression, often described as an enigmatic smile. The painting is celebrated for its masterful use of sfumato, a technique that creates soft transitions between colors and tones, giving the portrait a lifelike quality. Da Vinci's attention to detail and innovative techniques make this painting a timeless masterpiece.