The nave mosaics of the Basilica di Santa Maria Maggiore in Rome, commissioned by Pope Sixtus III following the Council of Ephesus in 431 CE and completed around 440 CE, constitute the earliest surviving monumental cycle of Old Testament narrative mosaics in Christian art. Twenty-seven panels - out of an original forty-two - survive above the nave colonnades, depicting scenes from the lives of Abraham, Isaac, Jacob, and Joshua. Together with the triumphal arch mosaics commissioned by the same pope, they form a complete theological program that was among the most ambitious visual statements of early papal Christianity.
The political and theological context of the commission is essential to understanding the mosaics' program. The Council of Ephesus in 431 CE had definitively declared Mary to be the Theotokos - the God-bearer, or Mother of God - in the Nestorian controversy, over against Nestorius's preference for the title Christotokos (Christ-bearer). Sixtus III built the Marian basilica partly as a visual celebration of Ephesus's definition, and the mosaics on the triumphal arch depict scenes of the Incarnation: the Annunciation, the Adoration of the Magi, the Presentation in the Temple, Herod and the Magi. The arch mosaics establish Mary's role in the Incarnation as the theological context within which the nave's Old Testament narratives must be read.
The nave mosaics present the patriarchal narratives of Genesis and the conquest narratives of Joshua as types of Christ and the Church - the standard methodology of early Christian typological interpretation. Genesis 18:2, where Abraham receives three visitors (interpreted in Christian tradition as a prefiguration of the Trinity, following the Philoxenia imagery that Rublev would later famously paint), appears in the nave cycle. The entire Abraham, Isaac, and Jacob sequence was read as a prefiguration of the Christian covenantal history: Abraham's call from Ur prefigures the Church's calling from the nations; Isaac's near-sacrifice on Mount Moriah prefigures Christ's sacrifice on Golgotha; Jacob's wrestling with the angel prefigures the Christian's wrestling with God in prayer and suffering.
Joshua 1:1 begins the narrative of the conquest of Canaan, which Christian typological reading interpreted as the entry of Christ - Joshua's name is the same as Jesus in Hebrew (Yeshua) - into the promised land of the Church. The Joshua panels, which occupy a significant portion of the surviving cycle, visualize this typological connection through an elaborate visual program of military triumph and divine assistance.
The mosaics' style is late antique Roman, closely related to imperial narrative art: the figures are depicted in dynamic movement against architectural and landscape backgrounds, with the episodic narrative structure of the Column of Trajan applied to biblical rather than military history. The visual language of Roman imperial triumph is here conscripted into the service of scriptural narrative, asserting that the Church is the legitimate heir of the Roman imperial visual tradition as well as the Hebrew scriptural tradition.
The basilica itself is the oldest church in Rome to maintain its original architectural form continuously, and Santa Maria Maggiore has never been demolished and rebuilt in the way that the old St. Peter's, San Giovanni in Laterano, and other major Roman churches were. The nave columns date from the fifth century, and standing in the nave with the surviving mosaics above is one of the most direct encounters with early Christian monumental art available anywhere.
The triumphal arch mosaics, which depict New Testament Incarnation scenes, were completed in the same program and read in concert with the nave's Old Testament cycle: the arch is the visual pivot from the Old Covenant's promise to the New Covenant's fulfillment, from type to antitype. Revelation 21:10 and 21:23 - the heavenly Jerusalem flooded with divine light - provide the eschatological horizon within which both cycles operate.
The basilica is a principal church of Rome (one of the four Major Basilicas) and is open to visitors. The mosaics are visible from the nave floor, though their considerable height makes detailed examination difficult without binoculars. The Esquiline Hill location in central Rome makes it easily accessible from the Termini station.
For further reading: Beat Brenk, Die frühchristlichen Mosaiken in S. Maria Maggiore zu Rom (1975); Richard Krautheimer, Rome: Profile of a City, 312-1308 (1980); Robin Cormack, Byzantine Art (2000); Jaś Elsner, Imperial Rome and Christian Triumph (1998); Ernst Kitzinger, Byzantine Art in the Making (1977).