The Karmavibhanga Panels

The 160 hidden panels do not form a continuous story, but each panel provides one complete illustration of cause and effect. There are depictions of blameworthy activities, from gossip to murder, with their corresponding punishments. There are also praiseworthy activities, that include charity and pilgrimage to sanctuaries, and their subsequent rewards. The pains of hell and the pleasure of heaven are also illustrated. There are scenes of daily life, complete with the full panorama of samsara (the endless cycle of birth and death).

Text adapted from Wikipedia (retrieved, March 8th 2012)

All the panels were photographed by Kasian Cephas in the 1890s, and these have recently been digitalised the Volkenkunde Museum in Leiden, and can be seen in low-definition (640px wide) files at The Hidden Base of Borobudur. There is also more information there and a description of some of the panels.