The best way to see the island of Ortigia is just to wander. It’s difficult to get lost (it measures just 1km by 500 meters and has lots of little streets that all look the same), but packed with over 2,500 years of history. We often come here at night as its a great place to soak up some Italian nightlife, wander past the harbor showcasing the yachts and sailing boats of the elite and also drop by the famous fountain of youth (La Fonte Aretusa). Half a dozen Greek poets wrote the tale of the nymph Arethusa, who was bathing in the Alpheus River in Greece one day when the god of that river took a liking to her. She begged for deliverance from his advances, and Artemis in pity turned the nymph into a spring, allowing her to escape underground. She traveled under the sea to emerge here, in Siracusa. Alpheus, though, was hot on her heels, and came gushing out in the same spot, mingling his waters with hers for eternity. Apparently this, to the Greeks, was romantic. They used to say you could toss a goblet into a spring at Arcadia in Greece and it would pop up here.
The most active volcano in Europe and by far the biggest dominating attraction in Eastern Sicily, Mount Etna is a must visit. If you head to Etna Sud you have the option to walk around some of the older craters on foot or take a cable car ride to 2,900m, from there it is a 2-4 hour round trip to the summit craters, although there is no need to go that far to get a good feel for the majesty of the mountain. The other point of departure is Etna Nord (Piano Provenzana) from where you may walk or take 4X4 buses up to the observatory at 2,400m. You may walk to the summit craters from there. I would highly advise to not go venturing to the main craters of Etna without a qualified guide.