BAPTISTERY (Gr. baptisterion, a large vase or basin), the name given sometimes to a separate building, sometimes to the portion of the church itself iu which the cere mony of baptism was performed. In the latter case, the B. was merely the inclosure. containing the font, to he se n. in most English churches. According to the earlier arrangements of the Christian church, however, the B. seems usually to have been a ,building standing detached from, though in the immediate vicinity of the church to which it appertained. Baptisteries, at first, were either hexagonal or octagonal, but afterwards became. polygonal, and even circular. The B. of St. Giovanni in Fonte, at Rome, commonly known as the B. of Constantine, is octagonal, whilst the church of St. Constantia, which was originally a B., is circular.
The celebrated B. of Florence is an octagonal structure, measuring about 100 ft. in diameter. It stands detached from, but in the immediate vicinity of the cathedral. It is built of black and white marble, in the style which Giotto is said to have introduced, and which is still peculiar to Florence. Internally, a gallery, which runs nearly round the whole building, is supported by 16 large granite column:, and the vaulted roof is decorated with mosaics by Andrea Tafi, the pupil of Chnabue. But the Magnificent
bronze doors, with their beautiful bass-reliefs, are the most remarkable feature of this famous baptistery. The most celebrated of the three doors was executed by Lorenzo Ghiberti, the earliest being the work of Andrea of Pisa. Fifty years were required fur their completion; and it is remarkable that the contracts for their execution arc still preserved. Next in importance, and of even greater size, is the B. of Pisa. It is circular in form, the diameter measuring 116 feet. Externally, it is divided into three stories. the two under ones being surrounded by columns, of which the upper arc smaller and more numerous than the under. The building is raised from the ground on three steps, and terminates in a pear-shaped dome, which is famous for its echo, the sides acting as whispering-galleries. The largest B. ever erected is supposed to have been that of St. Sophia. at Constantinople, which was so spacious as to have served on one occasion for the residence of the emperor Basilicus.