Vitale da Bologna: Adam and Eve, Cain and Abel
Abbey of Pomposa, Italy
The scene on the left follows the traditional iconography with two interesting exceptions: the serpent is itself indulging in the fruit, and the primal couple are seated. Other features are at least as old as the 4th century: the tree with fruit in its somewhat round crown; the couple being on either side of it, with Adam on the left; the snake coiling around the trunk; Eve's passing a fruit to Adam; and the couple's nakedness.
The two Cain and Abel scenes follow Genesis 4 straightforwardly.
View this image in full resolution.
Read more about images of Adam and Eve and about images of Cain and Abel.
Photographed at the abbey by Richard Stracke, shared under Attribution-NonCommercial-ShareAlike license.