Pisa is not only home to the most famous leaning tower in the world, it is also home to the largest Baptistery (which also leans a little) in Italy.
Circular in design and begun in 1152, its architecture is a mix of the Romanesque and the Gothic. The original architect is thought to have been Diotisalvi (also known as Deotisalvi and Deustesalvet), whose name is inscribed on an interior pillar. Unfortunately, almost nothing is known about him.
Funding soon became a problem and in 1163 it was decreed that, on the first day of each month, every family in Pisa should contribute one denaro to the building costs.
The Gothic decoration was added by Nicola Pisano and his son Giovanni between 1277 and 1297. The Battistero di San Giovanni (to give the building its proper name) was finally finished in 1363.
Pisa's baptistery is famous for its exceptional acoustics, the result of its having not one but two domes (the work of Cellino di Nese). The inner dome takes the form of a truncated cone, while the outer dome is hemispherical in design. The exterior of the dome is crowned with a bronze statue of St John the Baptist, thought to be the work of Turino di Sano (died 1427), a sculptor from Siena.
Of the four portals, the door that faces the Duomo is the most elaborate. It is flanked by two half-columns, while the inner jambs are decorated with stone reliefs. The lintel is divided into two tiers. The lower tier depicts episodes from the life of St John the Baptist. The upper tier depicts Christ, in the centre, flanked by the Madonna and St John the Baptist, with alternating angels and evangelists to either side.
Four pairs of columns, interspersed with four stone pillars, support the women's gallery.
The octagonal font (1246) is by Guido Bigarelli da Como (1220-c.1257).
The pulpit is dated 1260 and is the work of Nicola Pisano (c.1220-c.1284). This was Nicola Pisano’s first major commission and manifests a strong classical spirit. The conventional format for a pulpit had been invented a century before and consisted of a rectangular balcony (with narrative reliefs ranged along the sides) raised on columns and abutting a wall. Nicola’s pulpit is a departure from this model. It is freestanding and hexagonal in shape with a single, large relief on each of the six sides.
Although the pulpit is signed 'Nicola Pisanus', the master sculptor was aided by several assistants, including Arnolfo di Cambio and Lapo di Ricevuto.