The Battistero was built in 1167 and completed in the XV century with its upper pediment and the loggia.

It has an octagonal design, the symbol of baptisms, its walls are covered in brick, while the two façades overlooking the Piazza are in marble, and on one of these is the access door to the Battistero with its porch.

Inside, it is typically Medieval with Romanic and Gothic details, above the octagonal room is a large eight-arched cupola.

The vertical connections are located in two angular buttresses: they are spiral staircases leading to interior and exterior galleries.