There is a saying : if you want to see Greece-go to Sicily.
How true : The best preserved temples are in Sicily and not in Greece, hence if you will visit Greek temples in Greece after having visited the Sicilian ones, you will be truly disappointed.
Sicily was a highly regarded part of Magna Graecia, with the great Roman philosopher and orator, Cicero, describing Siracusa (Syracuse), as "the greatest and most beautiful city of Ancient Greece". In fact, by 300 BC, Siracusa was the most populous Greek city in the world and rivalled even Athens for political and military power, and at once stage defeating the mighty Athenian army in 413 BC during the Hellenic Peloponnesian Wars.
Agrigento and its Valle dei Templi (Valley of the Temples) features the largest collection of classical Greek ruins in the world. It is a must-see!
Dramatically perched along a long rocky scarp, among the extensive grounds are many well preserved temples, monuments and other buildings which create a truly surreal atmosphere. The temples are even more impressive at night when they are lit up by massive lights.
Other equally marvellous temples and amphiteathres are to be found in Segesta, (where each Summer, a series of classical Greek dramas are performed in Italian), Selinunte and Syracuse. But there are several, smaller-scale Greek ruins scattered everywhere all around the island, like in Akrai, Himera, Megara Hyblaea. By far the most breathtaking Greek Theatre of them all is located in the incredibly well preserved mediaeval city of Taormina, where you can enjoy sweeping views of the Mediterranean under the backdrop of the imposing volcano, Mount Etna.