Built in the 4C, this octagonal baptistry consists of two orders of arcades which support the vault adorned with superb mosaics commissioned by Bishop Neoni. The dome is decorated with an image of the Baptism of Christ, accompanied by a retinue of apostles, while the lower section portrays eight small temples with altars and thrones surmounted by the Cross, an iconography which refers to the preparation of the Almighty's throne for the Last Judgement.