Nearly everything in the Santa Croce relic chapel traces back to a single claimed source: Helena's reported journey to Jerusalem around 325 to 326, during which Christian tradition credits her with discovering the True Cross and gathering related Passion relics before returning to Rome. Unlike an archaeological find with a documented dig, this origin story rests entirely on later Christian historical writing rather than any contemporary excavation record, and the fragments, the Titulus Crucis, the nails and the thorns now at Santa Croce cannot be independently traced to a controlled find in the way even contested archaeological objects elsewhere in this atlas can.
What distinguishes Santa Croce's holdings from a single-object relic such as the Shroud of Turin is precisely this plurality: the chapel groups several distinct claimed relics under one collecting event, so that doubts about any one piece, most discussed regarding the Titulus Crucis, a fragmentary inscribed plaque rediscovered built into a wall of the church in 1492, do not necessarily extend to the others. The church presents the whole ensemble as a matter of continuous veneration since late antiquity rather than staking its claim on any one piece's scientific verification.