With its stacked domes, ornate tracery, and the gilded bronze of John the Baptist on top, the Baptistery is one of Pisa's more unusual buildings. Dedicated to St. John, it is the largest baptistery in Italy and has always played an important part in the religious life cycle encompassed by the Piazza dei Miracoli's monuments.
The exterior of the Baptistery of St. John presents as one ornate layer on top of another and those with a close eye to detail will notice that it is just a few centimeters taller than the Leaning Tower.
The lower arcades are Pisan-Romanesque in design while the upper section and two domes are later Gothic additions.
The dome is unusual in that, the half that faces the sea is finished in rich red tiles that glow at sunset while the other half is covered in lead plating designed to catch the rays of the rising sun.
The door lintel is finished with reliefs depicting scenes from the life of St. John as well as Christ sitting between the Madonna and the saint.
Work on the Baptistery started in 1152 to plans drawn up by Diotosalvi and it is widely believed he took inspiration for his design from the Rotunda of the Holy Sepulchre and the Mosque of Omar, both in Jerusalem. A century later, the Baptistery was remodeled by Nicola and Giovanni Pisano and was finally completed in the 14th-century when the domes were added.
Compared to the lavishly ornate exterior, the Baptistery's soaring interior, while breath-taking, is remarkably plain and austere, providing the perfect backdrop for the serious business of baptism.
On entering the baptistery, the immensity of the building is even more convincing than from outside. Here, in fact, we obtain an immediate sense of the proportions. The is 55 mts and the diameter 35.50 mts: bare values, but from inside, at this moments, the height and and amplitude have another meaning, so penetrating as to cause admiration and dismay. We are, in fact, under the huge vault of the dome and in front of a grandiose annular nave discreetly lighted by the numerous windows distributed all around. Our attentions will be very soon drawn by the Font and the Pulpit.
The octagonal baptismal font, dating from 1246 and attributed to Guido Bigarelli da Como, is the focal point of the interior. In the font's center is a bronze of St. John the Baptist, sculpted by Italo Griselli. The font sits on three steps - representing The Father, Son, and Holy Ghost and it is where, for many centuries, new babies were welcomed into the Roman Catholic life of the city. Galileo Galilei who, so legend says, made use of both the Leaning Tower and the Duomo for his scientific experiments was baptized here.
Also inside the Baptistery of St. John are 12 columns representing the 12 apostles and a hexagonal marble pulpit with classical sculptures carved by Nicola Pisano. Pisano's pulpit is an important marker in the artistic heritage of Italy as it dates from the year 1260; this is the year from which art historians date the start of the Italian Renaissance.
Before leaving the Baptistery, visitors should climb to the Upper Gallery and try out the remarkable acoustics. When a few notes are sung, they magically appear to echo around the upper chambers as whole chords. The Upper Gallery is also one of the best places in Pisa for taking a photo of the Leaning Tower.