AS THE CROW FLIES, ABOUT FIVE KILOMETERS SEPARATE THE VATICAN AND the Lateran – a long walk and a considerable distance on horseback. The spiritual energy flowing between them created an unlikely Christian decumanus, a major east–west street that now rivaled the ancient north–south cardo defined by Via Flaminia/Appia. To the medieval Roman and the foreign pilgrim this was the ultimate ceremonial path, Christian Rome's triumphal way. It conjured images of dazzling processions led by pontiffs and crowned heads of state, eventfully traversing the city with meaningful stops and attendant ritual. Processions such as the papal possesso, a ritual walk to the Lateran taken by the newly crowned pope, began at St. Peter's (Fig. 135). From there one moved down the length of the porticoed Via Cornelia toward the Tiber with the somber bulk of Hadrian's Mausoleum as the first beacon; across Pons Aelius, and through the Campus Martius, with pagan landmarks and Christian stations to the right and left, to the foot of the Capitoline; then skirting it along the north and east to enter the Roman Forum; passing through it to the crest of the Velia at the southeast end, where the Arch of Titus stood and opened the way down the slope to the Colosseum; and up again, to the top of the Caelian and the sprawling and spirited complex of the Lateran.

This was Via Lateranensis, Via Papalis, Via Maior: as close to an organizing central axis as medieval Rome ever had. But it was no triumphal route in the formal sense. Were it not for the power of processions to fashion continuity and cohesiveness through ceremonial movement, it would be seen for what it really was, a string of neighborhoods and a patchwork of streets of different width and indifferent rectitude, going uphill and down, and flanked by everything from rows of unassuming houses or yard walls to the still-proud marble frames of ancient theaters, monumental monasteries, and parish churches. It was no cardo or decumanus in the Roman sense. Via Papalis was not, in other words, the initial organizing determinant of the course of urban order, but the unanticipated and improvised reaction to the pull of two far-flung ceremonial centers.