depends mainly upon foreign visitors (some 30,000 annually),
who are attracted by the remarkable beauty of the scenery (that of the
coast being especially fine), the views of the sea and of the Bay of
Naples, and the purity of the air. The famous Blue Grotto, the most
celebrated of the many caves in the rocky shores of the island, was
known in Roman times, but lost until 1826, when it was rediscovered.
Another beautiful grotto has green instead of blue refractions; the
effect in both cases is due to the light entering by a small entrance.

The high land in the west of the island and the somewhat less elevated
region in the east are formed of Upper Tithonian and Lower Cretaceous
limestones, the latter containing Rudistes. The intervening depression,
which seems to be bounded on the west by a fault, is filled to a large
extent by sandstones and marls of Eocene age. A superficial layer of
recent volcanic tuffs occurs in several parts of the island. The Blue
Grotto is in the Tithonian limestones; it shows indications of recent
changes of level.

The earliest mythical inhabitants (though some have localized the Sirens
here) are the Teleboi from Acarnania under their king Telon. Neolithic
remains were found in 1882 in the Grotta delle Felci, a cave on the
south coast. In historical times we find the island occupied by Greeks.
It subsequently fell into the hands of Neapolis, and remained so until
the time of Augustus, who took it in exchange for Aenaria (Ischia) and
often resided there. Tiberius, who spent the last ten years of his life
at Capri, built no fewer than twelve villas there; to these the great
majority of the numerous and considerable ancient remains on the island
belong. All these villas can be identified with more or less certainty,
the best preserved being those on the east extremity, consisting of a
large number of vaulted substructures and the foundations perhaps of a
_pharos_ (lighthouse). One was known as Villa Jovis, and the other
eleven were probably named after other deities. The existence of
numerous ancient cisterns shows that in Roman as in modern times
rain-water was largely used for lack of springs. After Tiberius's death
the island seems to have been little visited by the emperors, and we
hear of it only as a place of banishment for the wife and sister of
Commodus. The island, having been at first the property of Neapolis, and
later of the emperors, never had upon it any community with civic
rights