The Baptistry is octagonal in shape with four apses and arched openings near the top. At one point in its history a heptagonal ambulatory encircled it. Along the external perimeter there was once a walkway that stopped at the eastern apse. The building is composed of brick, some of which were recycled from older structures. In its prime the interior would have been decorated with marble other richly detailed mosaics, but today only the dome's mosaic remains. Six graves have been discovered within the octagon. This is unusual because it is a
Baptistery, but it is not unheard of that baptisteries would contain graves in Late Antiquity because it is recorded that church councils had laws forbidding it. File:Ravenna — Arian Baptistery — Fragments 01.jpg|Wall decoration fragments File:Ravenna — Arian Baptistery — Fragments 02.jpg|Wall decoration fragments
Mosaic description Inside are four niches and a dome with
mosaics, depicting the
baptism of
Jesus by Saint
John the Baptist. Jesus is shown as a beardless, nude, and half-submerged in the River Jordan. A halo sits behind his head. John the Baptist is wearing a leopard skin, and his arm is outstretched, reaching for Jesus, and he rests his hand on Jesus' head. On the left stands a white-haired old man in a green cloak, holding a leather bag, as the personification of the river Jordan, a traditional Greek depiction of
river gods. His head is adorned with crayfish claws. This iconography is common in
Late Antiquity. He sits suspended in the water, his cloak composed of the same color as the rock the Baptist stands on. Above Jesus is the
Holy Spirit, in the form of a dove, spraying lustral water from its beak. Behind the figures in the central roundel is a background of luminous gold. Below, a double procession of the
Apostles, led in separate directions by
Saint Peter and
Saint Paul circle the dome, meeting at a throne with a jeweled
crucifix resting on a purple cushion. Behind their heads, halos are present. Saint Peter carries a key, and Paul carries a scroll. The throne between Saint Peter and Saint Paul symbolizes Christ's power. The key and scroll represent the authority and the power derived from Christ. The Apostles carry jeweled crowns that represent martyrdom. The Apostles are dressed in white, and their faces are nearly indistinguishable from each other. Additionally, the jeweled crowns may represent God's gifts given to the faithful disciples, the analogy then mirroring the act of baptism; the neophyte has been given the gift of being accepted as God's child now, and their sin washed away. Behind the Apostles gold has been used liberally to compose the background, interrupted by flora that juts from the ground. Beneath their feet is solid ground, unlike Christ, who has nothing underfoot, and the Baptist, who stands on a rock. It took the artists several years to complete these mosaics, as can be clearly seen from the different colors of the stones used to depict the grass at the feet of the apostles. The designs are quite simple, with a
gold ground, typically used in this era to infuse scenes with an ethereal glow. There are no historical records documenting the construction of the Arian Baptistery. == Similarity to Roman architecture ==