The city's best sight is its superb Archaeological Park of Neapolis, which includes a range of monuments in its limits, with more to be seen just outside (don't miss the vast Altar of Hieron, which can be seen from the little approach road).
Siracusa's Greek theatre (Teatro Greco) is one of the finest and largest of its kind. Cut directly into the rock, it was enlarged and modified several times over the centuries, and is still in use today - Greek plays are performed here in summer months.
Up above the Greek theatre is a low cliff with several caves cut into it, including a nymphaeum, where statues once surrounded the water feature.