The International Puppet Museum (Museo Internazionale delle Marionette)
has puppet shows every Friday. Details in English.

Visit Agrigento in January or February to see the splendid white almond blossoms:
Background on the local Almond in Blossom Festival
When is it?
Schedule of Festivals in Sicily
Popular Festivals around Italy

Access to the top of Mount Etna can change suddenly. Check on current conditions
before you visit.
Etna webcam
Etna updates (includes other volcanic areas in italy))
Etna volcanic activity
Weather conditions in the Etna area
Satellite imagery of 2001 Etna eruption

Parco Archeologico Greek Amphitheater
Scroll down to "Anfiteatro Romano"
Classical Greek and Roman plays are performed her on even numbered years.