This is a list of the highest prices paid for paintings. Very valuable paintings, if sold, are usually sold at auction.
Most of the world's most famous paintings are owned by museums, who very rarely sell them once acquired. As such, they are quite literally priceless; if for some reason paintings like the Mona Lisa were to become available, it is highly likely that they would sell for far higher values than the paintings listed below. The Guinness Book of Records lists the Mona Lisa as the highest insurance valuance for a painting in history. It was assessed at US$100 million on December 14, 1962, prior to the painting touring the U.S. for several months.  Taking into account the time value of money, this would be approximately equivalent to US$626,821,192.00 in 2004.
The Louvre chose to instead spend the money on security.
The price paid for any given painting is not necessarily a good indicator of that painting's beauty, cultural significance, or popularity. A notable high price may occur simply because two or more wealthy art collectors wanted the same painting and were willing to bid high.
† - Japanese businessman Ryoei Saito purchased both Portrait of Dr. Gachet (van Gogh) and Au Moulin de la Galette (Renoir) in 1990. Later, Mr. Saito threatened to have the van Gogh painting cremated with him at his death. Saito, 75 years old at the time, the honorary chairman of Daishowa Paper Manufacturing Co. , later stated: "What I really wanted to [express] was my wish to preserve the paintings forever." Saito, his aides explained, was using a figure of speech: threatening to torch the oils was just an expression of intense affection for the masterpieces. Later, Saito said he would consider giving the paintings to his government or a museum. Saito died in 1996. The fate of the van Gogh painting is still a mystery.