Basilica of Constantina, Sant'Agnese fuori le Mura (ruins)

Why Go

A roof over a graveyard

Come because this building answers a question most pilgrims never think to ask: what did Constantinian Rome actually build for its martyrs? Not a parish church. A vast covered cemetery, where ordinary Christians could be buried in the floor beside a martyr's grave, where families held funeral meals, and where Mass was said once a year on her anniversary. Standing at one end of it, with the scale visible and the roof gone, does more to explain fourth-century Christian practice than any amount of reading.

Constantina's cemetery, and why it was abandoned

The parish of the complex records that Constantina, daughter of the emperor Constantine, had the basilica built between 337 and 351 on family land near the place where Agnes was buried, and gives its dimensions as about 40.30 by 98.30 metres. Other accounts name 342 specifically. It is a substantial building by any standard and an enormous one for its date.

Its plan is the circiform type, sometimes called the circus basilica: three aisles, of which the outer two do not stop at the far wall but continue round behind the apse to form one unbroken ambulatory. About six examples are known in Rome and all belong to the Constantinian age. The shape is not decorative. It exists to let a continuous procession of people move around a burial area without obstruction.

The function follows from the shape. This was a coemeterium, a covered cemetery. The floor was given over to the graves of local faithful who wanted to lie near the martyr, the space was used for funeral banquets at burials, and the parish is explicit that regular liturgy was not what happened here: there was one Mass a year, on the anniversary of Agnes. Burial near the holy dead, ad sanctos, is one of the oldest instincts of Christian Rome, and this is what it looked like when an emperor's family paid for it.

The building was probably abandoned in the seventh century, when Honorius raised the present basilica directly over Agnes's grave. Once the Church built above the tomb itself, a covered cemetery beside it had no purpose. What remains are imposing ruins, best seen from the rear of the complex.

A three-aisled hall of about forty by ninety-eight metres whose side aisles curve round the apse end into a continuous ambulatory, giving the plan its resemblance to a circus. Roofless, with substantial lengths of perimeter wall standing. The Mausoleum of Santa Costanza was built against its flank, which is why the mausoleum sits at the angle it does.