The temple as seen today was built between 421 and 406 BC. Its architect may have been Mnesicles, and it derived its name from a shrine dedicated to the legendary Greek hero Erichthonius. The sculptor and mason of the structure was Phidias, who was employed by Pericles to build both the Erechtheum and the Parthenon. Some have suggested that it may have been built in honor of the legendary king Erechtheus, who is said to have been buried nearby.

Erechtheus was mentioned in Homer's Iliad as a great king and ruler of Athens during the Archaic Period, and Erechtheus and the hero Erichthonius were often syncretized. It is believed to have been a replacement for the Peisistratid temple of Athena Polias destroyed by the Persians in 480 BC.

Reference from Wikipedia: http://en.wikipedia.org/wiki/Erechtheum