BAPTISTERY (Baptisterium, in the Greek Church 445 COTUTTI)pLOV) was a hall or chapel in which the catechumens were instructed and the sacrament of baptism administered. It was commonly a circular building, although sometimes it had eight and sometimes twelve sides, and consisted of an ante-room (irpoaaLos axes) where the catechumens were instructed, and where before baptism they made their confession of faith, and an inner apartment where the sacrament was administered. In the inner apartment the principal object was the baptismal font (KoXvp./30pa, or piscina), in which those to be baptized were immersed thrice. Three steps led down to the floor of the font, and over it was suspended a golden or silver dove ; while on the walls were commonly pictures of the scenes in the life of the Baptist. The font was at first always of stone, but latterly metals were often used. Baptisteries belong to a period of the church when great numbers of adult catechumens were baptized, and when immersion was the rule. We find little or no trace of them before Constantine made Christianity the state religion, i.e. before the 4th century; and as early as the 6th century the baptismal font was built in the porch of the church and then in the church itself. After the 9th century few baptisteries were built, the most noteworthy of later date being those at Pisa, Florence, Padua, Lucca, and Parma. Some of the older baptisteries were very large, so large that we hear of cou;lcils and synods being held in them. It was necessary to make them large, because in the early church it was customary for the bishop to baptize all the catechumens in his diocese (and so baptisteries are commonly found attached to the cathedral and not to the parish churches), and also because the rite was performed only thrice in the year. (See BAPTISM.) During the months when there .were no baptisms the baptistery doors were sealed with the bishop's seal. Baptisteries, we find from the records of early councils, were first built and used to correct the evils arising from the practice of private baptism. As soon as Christianity made such progress that infant baptism became the rule, and as soon as immersion gave place to sprinkling, the ancient baptisteries were no longer necessary. They are still in general use, however, in Florence and Pisa. The name baptistery is sometimes also given to a kind of chapel in a large church, which served the same purpose. (Cf. Hefele's Concilien, passim ; Du Cange, Glossary, article " Baptisterium ;" Eusebius, Hist. Eccl. x. 4 ; Bing-ham's Antiquities of the Christian Church, book xi.)