The Parthenon comes immediately into view after the visitor enters the Acropolis through the Propylaea. Also dedicated to Athena, this large temple built entirely of marble is considered the greatest masterpiece of Greek architecture for its harmonious proportions, its architectural refinements, and the elegant sculptures that decorated it. The temple was designed by Greek architects Ictinus and Callicrates and was constructed from 447 to 438 bc. It measures 31 by 70 m (102 by 230 ft).