The temple itself is a protective home for the real showpiece, the cult statue of Zeus. This statue of Zeus, which was one of the Seven Wonders of the Ancient World.
I learned that a sculpture of Zeus was inside the temple, called the Chryselephantine (was carved from ivory ( the ivory was soaked in a liquid that made it softer, so it was probably both carved and shaped as necessary) then covered with gold plating (thus chryselephantine) and was seated on a magnificent throne of cedarwood, inlaid with ivory, gold, ebony, and precious stones. Statue was approximately 43 feet high. Magnificent! (Online Olympia, Greece)
The photo is the ruins of what was once a massive building.