The rocks matter, but they belong to a much larger system. Submarine lava, uplifted clay, fishing harbours, thermal springs, coastal towers, churches rebuilt after earthquakes and paths descending a fault scarp all occupy a narrow band between Etna and the Ionian Sea.
The repeated name Aci is not a decorative regional label. Aci Castello, Aci Catena, Aci Sant’Antonio and Aci Bonaccorsi, together with Acireale and the sea villages, preserve fragments of a territory once understood as Jaci. Its later divisions created distinct municipalities, devotions, economies and urban forms.
A complete guide must therefore move town by town. Myth can open the door, but geology, archives, material culture and living communities must decide what is actually seen.