The Castello Caldoresco is a low square Renaissance fortress in the centre of the hill town — four corner bastions, a wide central courtyard, and walls that once looked out unobstructed over the sea. Built in the mid-15th century for the Caldora family by Giacomo Caldora, one of the great mercenary captains of the era, it later passed to the d'Avalos.
The interior is now used for civic functions and rotating exhibitions; the courtyard is open to walkers in the day. The most photogenic angle is from Piazza Rossetti below — the corner bastion rising directly out of the medieval walls.