Founded in 1363, this substantial monastery is generally considered to be the finest remaining example of Caprese architecture and today houses a school, a library, a temporary exhibition space and a museum with some evocative 17th-century paintings. Be sure to look at the cloisters, which have a real sense of faded glory (the smaller is 14th century, the larger 16th century).
To get here take Via Vittorio Emanuele III, east of Piazza Umberto I, which meanders down to the monastery.
The monastery's history is a harrowing one: it became the stronghold of the island's powerful Carthusian fraternity and was viciously attacked during Saracen pirate raids in the 16th century. A century later, monks retreated here to avoid the plague and were rewarded by an irate public (whom they should have been tending), who tossed corpses over the walls. There are some soothing 17th-century frescoes in the church, which will hopefully serve as an antidote as you contemplate the monastery's dark past.