now CASTIGLIONE, in Ancient Geography, an old and at one time important city of Latium, on the Via Praenestina, between 12 and 13 miles from Rome. Long before the foundation of Rome, Gabii seems to have been one of the largest and most populous of the Latin cities. According to an old tradition, noticed both by Dionysius and Plutarch, Romulus and Remus are said to have been educated there. During the period of regal Rome, Gabii appears to have kept its ground against the growing power of that city, and only fell into the hands of Tarquin the Proud by a stratagem contrived by his son Sextus. On the expulsion of the Tarquins, Sextus took refuge at Gabii, and was murdered by the inhabitants in revenge for his treachery. After this period Gabii always appears in history as the ally or dependent of Rome, and gradually fell into such a state of decay as to become a proverb of desolation. In this condition it remained till the reign of Tiberius, when the fame of its cold sulphurous waters tended to revive it considerably. After the third century it disappears altogether from history. The only relic of the ancient Gabii now visible is a temple of Juno on a hill now crowned by the ruins of the mediæval fortress of Castiglione.

In the neighbourhood of Gabii were valuable and extensive quarries of an excellent building-stone, known as the "lapis Gabinus," which was largely used by the Romans. It was a hard and compact variety of the volcanic tufa found in abundance throughout the Campagna, and closely resembled the "lapis Albanus," to which, however, it was superior.