Salman Khan corrects an incorrect calculation from the previous video. It was wrong because there was no actual year zero. He discusses correctly determining the year based on the common AD, BC, or BCE abbreviations.

Plato's Allegory of a Cave is represented in this animated video. It shows different characters whose dialogue expresses their importance and symbolism.

The History ChannelÕs celebration of Greek World History Week begins with a look at Athens. Burned by invading Persians and reconstructed by Pericles, the animated reconstructions let viewers tour this most famous city of the ancient...