The Baptistry of St. John (Italian: Battistero di San Giovanni) is a religious building in Pisa, Italy. It started construction in 1152, in replacement of an older baptistry, and completed in 1363. It is the second building, in the chronological order, in the Piazza dei Miracoli, near the Cathedral and the famous Leaning Tower.
The architect was Diotisalvi, whose signature can be read on two pillars inside the building, with the date 1153
The structure is 54.86 m high, with a circumference of 107.24 m, and is the largest baptistry in Italy. The Baptistry has an example of the transition from the Romanesque style to the Gothic style: the lower registers are in the Romanesque style, with rounded arches, while the upper registers are in the Gothic style, with pointed arches. The Baptistry is constructed of marble, plentiful and often used in Italian architecture.