<Tr> <Th> Artist </Th> <Td> Leonardo da Vinci </Td> </Tr> <Tr> <Th> Year </Th> <Td> c. 1503--06, perhaps continuing until c. 1517 </Td> </Tr> <Tr> <Th> Medium </Th> <Td> Oil on poplar panel </Td> </Tr> <Tr> <Th> Subject </Th> <Td> Possibly Lisa Gherardini </Td> </Tr>

Who painted the mona lisa and why is she smiling