This The temple of Zeus.  As you can see, all the columns were knocked down in some earthquake.

This is the largest ancient temple on the Pelopennesos.  Build by the architect Libon of Elis.  The surviving pedimental sculptures and metopes are masterpieces of the severe style.  The main object of worship in the temple was the gold and ivory statue of Zeus by Pheidias.  Only the foundations of the temple have been preserved, together with a large number of architectural parts toppled on the ground.