The art essay

Triumphal Arch Mosaic of the Church of Saint Praxedes by Unknown

 A city built on the witness of martyrs

O happy Rome! who in thy martyr princes’ blood,

A twofold stream, art washed and doubly sanctified.

All earthly beauty thou alone outshinest far,

Empurpled by their outpoured life-blood’s glorious tide.


Drawn from a 5th-century Latin hymn, the Decora lux, these poetic words honor the two princes of the Apostles and “twin” founders of Christian Rome: Saints Peter and Paul. To this day, the solemn tones of this ancient hymn fill the vesperal twilight of the great dual feast that commemorates their martyrdoms. These words also adorn the rooftop of Rome’s North American seminary. Perched atop the Janiculum Hill, the seminary’s belvedere casts a sweeping gaze across the width and breadth of the Eternal City. This inscribed encomium hails the city below—one that bore witness to the ignominious deaths of Peter, Paul, and many members of their flock nearly 2,000 years ago. Today, resplendent art and architecture have blossomed over these martyrs’ graves.

 The art and architecture of Santa Prassede

Within the shadow of Saint Mary Major stands one such martyr shrine: the 9th-century Church of Santa Prassede. Relatively small in comparison to the major basilica it flanks, Santa Prassede’s unobtrusive size and plain brick exterior conceal rich artistic and spiritual treasures.

Upon entrance to the church, visitors are initiated into a new way of seeing. As our eyes adjust from the bright light of day, we find ourselves standing within a veritable jewel box, wherein imposing figures loom large on mosaic walls. The fire of candles and hanging lamps combines with the soft light from the clerestory windows to enliven a sea of tiny glass and golden tesserae. Each of these reflective colored squares is set at a slightly different angle in the gracefully undulating cement of the walls, creating a shimmering, ethereal effect. This movement of flickering light over cut glass creates the impression of weightless walls, and enlivens the figures of saints and angels, whose frontal gazes engage and invite viewers to contemplate a transcendent realm bathed in light.

The swirling designs of the cosmatesque marble floor guide the viewer’s eye up the central aisle toward a great triumphal arch which dominates the liminal space that demarcates nave from altar. This arch, while quoting the visual language of pagan Rome, does not fete a temporal victory. Instead, it stands in monumental testimony to the eternal triumph of Christ and his Church. Like the proscenium arch of a theater, it invites the onlooker to behold the liturgical drama taking place just beyond it. Indeed, the arch’s largely processional scenes bear a certain mimetic resemblance to the celebration of the Christian mysteries.

In its upper register, Saints Peter and Paul—identifiable by their characteristic coifs and apostolic accoutrements—welcome crowds of martyrs into the heavenly city. White-robed youths hail their entry in the spandrels below. With wide eyes fixed upon their goal, the martyrs’ feet press forward toward the open gates of paradise. Ruby-red poppies flourishing in their path allude to the spiritual fecundity of their spilled blood, while azure clouds above indicate the gathering of the heavenly hosts. In a gesture that recalls the obeisance due an earthly emperor, their covered hands offer imperishable crowns of martyrdom to Christ. The sweeping diagonal lines of the composition guide the viewer’s eye inside the bejeweled walls of the heavenly city, wherein Apostles converge upon the central, dominating figure of Christ. The celestial city of Santa Prassede’s triumphal arch is entirely unique in early medieval church decoration in that it contains no interior landmarks, only saintly inhabitants.

Above the altar, a barrel-vaulted ceiling of midnight blue mosaic bestrewn with celestial luminaries suggests the union of the heavens and the earth that occurs during the Eucharistic sacrifice. Directly below the altar, an inconspicuous staircase descends out of view into the crypt that houses the mortal remains of over 2,300 Roman martyrs. The relics were transferred to this site from the catacombs by Pope Paschal I († 824), who also oversaw the church’s restoration and mosaic decoration. This number includes the church’s namesake, Saint Praxedes (in Italian, Prassede), a disciple of Peter and Paul who fastidiously protected the remains of her beloved Christian comrades. She is said to have used a sponge to collect and deposit the blood of the martyrs into a small well located underneath the present-day church.

 The blood of the martyrs, the seed of the Church

Christian Rome is a city built upon the faithful witness of martyrs. As Church Father Tertullian famously wrote in his 2nd-century Apologeticus, “The blood of the martyrs is the seed of the Church.” Of course, here his reference to the Church alludes to the People of God. However, we need only consider the sheer number of martyr shrines that crowd Rome’s highways and byways to understand the architectural manifestation of this saying. Over the pauper’s grave of a fisherman from Galilee, crucified as a criminal on the outskirts of the city, and hastily interred on Vatican Hill, now stands the greatest edifice of them all: Saint Peter’s Basilica. Through the centuries, Rome’s skyline has filled with domes that hover over her numerous martyr shrines; they nod in silent allegiance to their massive counterpart that marks the grave of Peter.

The Church of Santa Prassede, though humble and hidden among these great shrines of Rome, powerfully evokes Tertullian’s claim. Arching above a foundation of relics, its mosaics visually manifest the beauty of martyrial sacrifice and epically memorialize the martyrs’ eternal triumph. What’s more, the tiny glass and stone tesserae that fit together to form this stunning mosaic program remind the viewer that the living stones (1 Pt 2:5) of faithful witnesses unite to form a spiritual dwelling place of God (Eph 2:22).

Amy Giuliano

Studied theology in Rome
and currently studies sacred art at Yale

Triumphal Arch Mosaic of the Church of Saint Praxedes  (9th century), artist unknown (completed by a team of Carolingian mosaicists), Basilica of Santa Prassede, Rome, Italy. © Photo Scala, Florence / Fondo Edifici di Culto - Min. dell'Interno.