In Christian architecture the baptistery or baptistry (Old French baptisterie; Latin baptisterium; Greek βαπτιστήριον, 'bathing-place, baptistery', from βαπτίζειν, 'to baptize') is the separate centrally planned structure surrounding the baptismal font. The baptistery may be incorporated within the body of a church or cathedral and be provided with an altar as a chapel. In the early Church, the catechumens were instructed and the sacrament of baptism was administered in the baptistery.
The sacramental importance and sometimes architectural splendor of the baptistery reflect the importance of baptism to Christians. The octagonal plan of the Lateran Baptistery, the first structure expressly built as a baptistery, provided a widely followed model, which might be twelve-sided, or even circular as at Pisa. In a narthex or anteroom the catechumens were instructed and made their confession of faith before baptism. The main interior space centered upon the baptismal font (piscina), in which those to be baptized were immersed thrice. Three steps led down to the floor of the font, and over it might be suspended a gold or silver dove. The iconography of frescos or mosaics on the walls were commonly of the scenes in the life of Saint John the Baptist. The font was at first always of stone, but latterly metals were often used.
The Florence Baptistery (Italian: Battistero di San Giovanni), also known as the Baptistery of Saint John, is a religious building in Florence, Italy, and has the status of a minor basilica. The octagonal baptistery stands in both the Piazza del Duomo and the Piazza San Giovanni, across from Florence Cathedral and the Campanile di Giotto.
The Baptistery is one of the oldest buildings in the city, constructed between 1059 and 1128 in the Florentine Romanesque style. Although the Florentine style did not spread across Italy as widely as the Pisan Romanesque or Lombard styles, its influence was decisive for the subsequent development of architecture, as it formed the basis from which Francesco Talenti, Leon Battista Alberti, Filippo Brunelleschi, and the other architects created Renaissance architecture. In the case of the Florentine Romanesque, one can speak of "proto-renaissance", but at the same time an extreme survival of the late antique architectural tradition in Italy, as in the cases of the Basilica of San Salvatore in Spoleto, the Temple of Clitumnus, the church of Sant'Alessandro in Lucca.