One of the most expensive art works ever produced, the murals painted by graffiti artist David Choe for Facebook's Palo Alto office in 2005 now have a projected market value of $500 million. Facebook originally offered Mr. Choe $60,000 to paint the murals, but the graffiti artist chose Facebook stock instead. Facebook clearly appreciated the value of Mr. Choe's murals. When the company outgrew its original offices in Palo Alto, the mural-covered concrete walls were removed from the building and placed on display in the new offices.