BAIÆ, an ancient town of Campania, Italy, situated between the promontory of Misenum and Puteoli, on the Sinus Baianus, and famous for its warm springs and baths, which served the wealthier Romans for the purposes both of health and pleasure. The variety of these baths, the mild ness of the climate, and the beauty of the landscape, captivated the minds of the opulent nobles. The habitations at first were small and modest ; but increasing luxury added palace to palace, and enterprising architects, supported by boundless wealth, laid the foundations of new erections in the sea. From being a place of occasional resort for a season, Baiae grew up into a city, and the confluence of wealthy inhabitants rendered it as much a miracle of art as it had before been of nature, though it never attained the rank of a municipium, but continued to be dependent on Cumse. C. Marius, Lucullus, Pompey, and Julius Caesar are among the most remarkable of those who gave é to Baice during the republic ; and at a later period it was a favourite resort of Nero, Caligula, Hadrian, and Severus. It flourished till the days of Theodoric the Goth ; but its destruction followed quickly upon the irruption of the northern conquerors. When the guardian hand of man was withdrawn, the sea reclaimed its old domain ; moles and buttresses were washed away ; and promontories, with the proud towers that once crowned their brows, were under mined and tumbled into the deep. Innumerable ruins, heaps of marble, mosaics, and other relics of the past, attest the ancient splendour of the city. The most remark able are the so-called temples of Mercury, Venus, and Diana, and various buildings which, rightly or wrongly, have been assigned to the more famous of those who are known to have had villas in the town. The Castello di Baja was built in the 16th century by Pietro di Toledo. Long. 14 3 E., lat. 40 50 N.