AD CORPUS, BASILICA. — This is the technical term used by archaeologists to designate a basilica built near or over the body of a saint, in his honor or in order to facilitate his liturgical cult.
Since in antiquity this cult was paid only to martyrs, and since they ordinarily lay buried in a cemetery or had subsequently given rise to one, the basilica ad c. in reality amounted to a cemetery and suburban basilica erected in honor of a martyr. As such, it represents an exception to the
rule according to which the ordinary basilica or church was built in urban centers and contained the body of no martyr, even if it was sometimes dedicated to one. These were also the only churches ordinarily officiated in and provided with their own stable clergy; those ad c., on the other hand, had only a custodian or mansionarius, who might be any ecclesiastic, and were officiated in only on the martyr’s feast and occasionally at other times during the year.
Since the basilica ad c. was built in a cemetery, amid tombs and mausoleums, it was generally erected on very difficult terrain. Its forms, therefore, were almost never regular, and only exceptionally were they of great proportions; moreover, although the basilical form is absolutely predominant, it is often not a pure one, but serves merely as a framework.
Particularly noteworthy is the tendency to enlarge the space around the altar in order to make room for the multitude of the faithful; this made the use of a spacious transept almost standard. The devotion of the faithful, who sought to be buried near the martyr (v. AD SANCTOS), then gave rise to many appendages of a cemetery character; indeed, the church itself ordinarily became a vast cemetery (earth graves beneath the pavement, lateral arcosolia, sarcophagi in every compartment, attached mausoleums). Furthermore, in order to draw nearer to the venerated tomb, when it was situated deep underground, crypts were constructed, generally semicircular, with horseshoe-shaped corridors. This practice subsequently spread also to urban churches, especially when they housed the bodies or relics of martyrs.
The essential requirement for satisfying the desire to draw near to the venerated body was that the altar should be placed either above it or very near II. For this purpose, the ground was often cut away deeply so as to bring the church down to the level of the venerated tomb, or a small church was even arranged almost entirely underground (S. Ermete, S. Agnese, SS. Nereo e Achilleo in Rome); at times special passages were established between the tomb and the altar; at times, when it was impossible to make the center of the church coincide with the tomb, the altar was placed eccentrically, provided that it remained over the martyr’s tomb. In this way the martyr remained as though buried beneath the altar; he guarded the altar, as it was said. From this there began the conception of the altar-tomb, which gradually came to be superimposed upon and then also to replace the primitive conception of the altar-table.
For the bibliography V. BASILICA. Antonio Ferrua