English: The Baptistery in Pisa, devoted to St. John the Baptist, stands in front of the west facade of the Cathedral; it was begun in the middle of the 12th century as replacement of a previous Baptismal building, oldest and smaller, octagonal shape, which was North ( it ruins lie in the ground below the Monumental Cemetery).

Originally built in "romanic" style by Diotisalvi, it was supposed to be a mix between the Anastasis of the Holy Sepulchre and the Mosque of Omar, considered at the time the Temple of Solomon (both located in Jerusalem ). Therefore the structure is heavily symbolic; it presents a curious truncated conical vault, which covers only the inner circle of the pillars... originally the top part was open to symbolize the filling of the Baptismal font, then later the vault was masked by another hemispheric vault and the folder was closed.

It remained unfinished until the 14th century when Nicola Pisano and his son Giovanni, modifying in "Gothic" style, the original project, terminated the lodge, the upper floor and the vault. It is the largest Baptistry in Italy, in its inside there are 12 columns as the number of the Apostles, a baptismal font with 8 sides (number indicating the "not created" day) and the same is placed on 3 steps to symbolize Father, Son and Holy Spirit! The Baptismal font is attributed to Guido Bigarelli da Como.

It is a very simple and strangely internal, devoid of decorations where the pulpit of Nicola Pisano sticks out, but it has a special feature known all the world t, in fact, thanks to particular architectural structure of the cover, it shows an outstanding acoustics with the echo that shapes and remembers the sound of the organ!

The Baptistery is certainly the most "international" Medieval buildings in Pisa.