Above the port lies the old penal colony. The prison lasted for 100 years, and only closed down in the mid-1980's. Lots of the old buildings remain. The prisoners undertook a lot of terracing, greatly extending the cultivated area that had been left by the Romans.
After the Romans the island hosted a number of monasteries and hermits, and this rather sweet ruin presumably dates from that period. Beneath it lies a cemetery which looks as if it is still in use.
After the monks came, depending on which guide book you read, the pirates or Saracens. Many identify them completely. We still have some research to do on the Saracen history of Italy; unlike the Moors in Spain, there are no great buildings left, no visible mark on the landscape. Either they didn't build them, or they have been overwritten by the luminous work of the Renaissance. It will be interesting to learn more as we travel south.