The Neonian Baptistry is Ravenna’s oldest monument, at least with regards to its construction, dating to the end of the 4th or the beginning of the 5th Century. It’s a simple octagonal brick building with four large niches towards the exterior and doors that are buried; the original is about three metres below the present door. Bishop Neone decorated the Baptistery with splendid mosaics around 450. The interior has fantastic mosaic decoration of Hellenic-Roman style with the remains of stucco works and marble. In the centre is an octagonal font of Greek marble and porphyry, which retains some original fragments.