The only on of the Zodiac constellations that is not human or animal, Libra depicts a set of scales. It was the Babylonians who first placed a set of scales in the sky, but the Greeks saw this formation as the claws of the nearby Scorpius. Later, to the Romans, Libra came to be a symbol of Julius Caesar, and his fairness and justness.

Libra - Libra are the scales that balance justice. They are held by the goddess of divine justice, Themis. Why exactly she is placed among the stars I haven't yet found out, but it is interesting that Libra shines right beside Virgo which represents Astraea, daughter of Themis.