1. Mona Lisa by Leonardo da Vinci

2. Madonna Litta by Leonardo da Vinci

3. Sistine Madonna by Sanzio Raphael

4. The Last Supper by Leonardo da Vinci

5. Creation of Adam by Michelangelo

6. Birth of Venus by Sandro Botticelli

7. Liberty Leading the People by Delacroix

8. Arnolfini Marriage by Jan van Eyck

9. The Ballet Dancer by Edgar Degas

10. Black Square by Kasimir Malevich

11. The Japanese Bridge by Monet

12. The Persistence of Memory by Salvadore Dali

13. Flight of a Bee by Salvadore Dali

14. Sunflowers by Vincent van Gogh

15. Vitruvian Man by Leonardo da Vinci

16. Death Of Marat by Jacques-Louis David

17. Ship of Fools by Hieronymus Bosch

18. Tower of Babel by Pieter Brueghel the Elder

19. Icon of the Trinity by Andrei Rublev

20. Union of Earth and Water by Peter Paul Rubens

Source: Ask Wiki

The Greatest Paintings of All Time. Part 2

The Greatest Paintings of All Time. Part 3