How Sperlonga was built and evolved over time

Sperlonga was built upwards for safety and outwards in rings.

The settlement grew on the promontory of San Magno, a spur of the Aurunci standing 65 metres above the sea, chosen as a defence against Saracen raids from the water and as an escape from the marshes below. The castrum Speloncae is documented in the tenth century, and the town developed around its castle progressively, in concentric circles.

In the eleventh century the settlement was walled. Two gates survive from that circuit — the Portella, also called Porta Carrese, and the Porta Marina — and both carry the arms of the Caetani.

The defensive system extended along the coast. Torre Truglia was built in 1532 on the point of the promontory the town stands on; it was destroyed during a raid by Barbarossa, rebuilt in 1611 and destroyed again in 1623. The Torre del Nibbio is built into a baronial castle facing the little central square, and the Torre di Capovento, three kilometres south, also dates from 1532 and was used as a customs house from 1820.

Rebuilding between the seventeenth and nineteenth centuries gave the town the form it has now, called a testuggine — tortoise-shell — along with its churches and noble palaces.

The oldest architecture is down at sea level and Roman. Tiberius's villa enlarged an earlier late-Republican one, with rooms arranged around a portico, and its natural grotto was fitted out as a summer dining room complete with water features.