PLATONIA. - From platoma or platomum: a marble slab.
The term is found used in the Liber Pontificalis, in the biography of Liberio, of whom it is said that « ornavit de
platomis marmoreis sepulcrum sanctae Agnetis » (Lib. Pont., I, p. 208); in the biography of Pope Damaso, who dedicated « platomam in catacumbas » (ibid., I, pp. cv and 214, nn. 9 and 10); in the biography of Sisto II it is said that he faced the enclosure around the tomb of s. Lorenzo with porphyry « platomas » and placed in the cemetery of Callisto a « platomam » to commemorate there the names of the bishops buried there. This slab was reconstructed by G. B. De Rossi (Roma sotterr., II, Roma 1867, pp. 33 sgg.) using the list transcribed in the Turonense collection (id., Inser. Christ., II, ivi 1888, p. 66, n. 25 a). In the Middle Ages the apostolic memorial « in catacumbas » gradually came to be localized to the west of the Basilica itself, and that mausoleum erected by the prefect of Rome Vivenzio, friend and supporter of Damaso, where the martyr Quirino, bishop of Siscia, was subsequently buried, came to be called p.