Piazza del Duomo. Battistero di San Giovanni - Interno

The Baptistry was founded in 1152, but it took more than two centuries to complete. The first stage of construction, up to the top of the first row of arches, was directed by the architect Diotisalvi. At the beginning of the 13th century Guidetto took over, and supervised the ornamentation of the doors and walls, up to the top of the circular aisle. After 1260, Nicola Pisano worked on the outside wall, up to the level of the archlets in the external gallery, but it was Giovanni Pisano who added the pediments above. Work was then suspended for a long time, beginning once more in the mid 1300s, when the women’s gallery was completed and the baptistery roofed over. At the bottom, the outside of this circular building presents a row of round dead arches, broken by slit windows and four doors and supported by pillars against the walls. Above these is a gallery of arched columns with ornately carved pediments. Empty spaces in this gallery are due to some statues being transferred to the nearby Opera del Duomo Museum. These arches are decorated with human heads carved by Nicola Pisano and his workshop, in and after 1265.
Above, rises the dome, skirted by a row of triangular fronted marble aedicules completed with a pair of pinnacles. At the top is a statue in gilded copper of St. John the Baptist, made by Turino di Sano da Siena in 1395
The door facing the Cathedral was decorated in about 1203-1204 by sculptors of Greek-Byzantine culture; the cycle is flanked by two columns carved in spirals of foliage.