Leonardo da Vinci(达·芬奇)，born in Italy, began painting the Mona Lisa, one of the most famous paintings of all time, in 1503. He was working on a special painting for a church at the time, but it was not going well. It is said that an Italian businessman asked him to paint a portrait(自画像) of his wife named Madonna Lisa del Giocondo. People thought she was the woman in the Mona Lisa.

The painting is only 77 cm by 53 cm and da Vinci painted it with oil on wood. After da Vinci finished the painting in 1506, the French King told him to visit France, and he took the painting with him.

Today the Mona Lisa is kept in the Louvre, an art museum in Paris, and about six million visitors go there to take a look every year. Visitors come to look carefully at her smile and her eyes. They try to find out what she was thinking about as she posed. Artists look closely to see what special skills Leonardo used to make her hands look so natural. How did he create the shadowy background behind her? 

On August 22, 1911 , an artist named Louis came to the Louvre Museum to study and copy the Mona Lisa , as artists and students could do it . It was a Tuesday, which is important because on Monday the museum was closed. Louis came into the room but the painting wasn't there. Did someone move it? He waited for a while . Then he asked a guard about it. When the guard came back, he had very bad news. The Mona Lisa was missing. In fact, Vincenzo Peruggia, a worker at the Louvre, took the painting away. He took it out of the museum by hiding it under his coat. Two years later, police officers found the painting under his bed after he tried to sell it.

In 1962, the Mona Lisa was taken to Washington and New York on show. For the journey, to keep the painting safe，the insurance company(保险公司) set the price of it at 100 million dollars, making it the most expensive painting ! Today, the painting would be over 700 million dollars. In fact, what makes it the most expensive painting is that it's priceless.