Volto Santo ai Prati was a 19th century devotional oratory, now demolished, on the Via Pietro Cavallini in the rione Prati. The postal address was Lungotevere dei Mellini 7, the presbytery round the back.
The dedication was to Jesus Christ, under his aspect of the Holy Face.
The remote origins of this lost oratory lie in the visions of Christ experienced by a French Carmelite nun of Tours called Soeur Marie de Saint-Pierre. The devotion to the Holy Face of Jesus that she initiated was taken up by Leo Dupont, and when he died in 1876 his house was converted by the city's bishop into the first Oratory of the Holy Face. To administer this, a diocesan congregation of priests called Priests of the Holy Face was set up.
The devotion stressed the need for reparation for acts of blasphemy and the "violation" of the Church's feast-days. The latter concerned those nations where the major feast-days of the Roman Catholic Church were originally protected in secular law by the prohibition of paid work and commercial activity, but where the protection had been removed as societies modernised and secularised. This occurred firstly in France at the French Revolution. At Rome, the conquest of the city by the Kingdom of Italy and the downfall of the Papal government in 1870 brought about this "violation" of some (not all) such feast-days, and also engendered a strong hostility among some native Romans to the continued Papal claims to be the legitimate secular government of Rome. The various types of socialism familiar in the 20th century were being erected as political movements at this time, and were becoming influential in Rome. In response, Pope Leo XIII expressed the desire that an Oratory be established by the Priests at Rome in expiation for this "blasphemy and violation". He did this in 1885 when he approved the devotion.
In response, the Priests opened the Roman oratory in 1891. This was paid for by public subscription in France. The first superior was Fr Jean-Baptiste Fourault, who wrote several books about the devotion.
The abbé Fourault returned to France in 1905, and it seems that the oratory was demolished for redevelopment shortly afterwards.
The writer has not been able to find any photos or illustrations of this oratory, nor any published descriptions of it.
The oratory and its attached presbytery occupied the south side of the Via Marianna Dionigi between its junctions with the Via Pietro Cavallini (on which the oratory entrance stood) and the Lungotevere dei Mellini.