Santa Maria Addolorata dei Sacconi Rossi or Oratorio dei Sacconi Rossi is a deconsecrated 18th century chapel in the old Franciscan monastery attached to the north side of the basilica of San Bartolomeo all'Isola. This is on the Isola Tiberina.
The Confraternità dei Devoti di Gesù al Calvario was founded in 1760, initially as a lay confraternity with the aims of meditating on the Passion of Christ and praying for the souls of those in Purgatory. They quickly took up the work of burying any unclaimed dead bodies found in the Tiber, of which there was apparently a plentiful supply. They did this at night, and in their processions wore voluminous red habits, hence the nickname Sacconi Rossi. They also cared for people working on the river around the island.
In 1768 the Confraternity leased premises in the Franciscan convent building next to San Bartolomeo. In 1780 they leased a large ground floor storeroom and fitted it out as a chapel for their own use, and four years later obtained permission to turn the cellar underneath into a charnel house for the bodies of deceased members. The French occupiers at the end of the century stopped this by requiring all burials to be in the new Campo Verano cemetery. The prohibition was repealed in 1815, but re-enforced in 1832 after an outbreak of cholera. Burials were allowed again from 1851, but were finally abolished in 1871. In the 19th century it appears that the confraternity had become little more than a burial club, because the abolition of their burial rights seriously affected membership.
By the latter half of the 20th century the membership had almost died off, but the Confraternity of Santa Maria dell'Orto took an interest and began holding ceremonies to commemorate those drowned in the river as from 1983. From 1988 the Hospitallers of St John of God (nicknamed the Fatebenefratelli), at the hospital of San Giovanni Calibita on the island, took over the rights and privileges of the Sacconi Rossi.
The headquarters of the confraternity are now at Piazza Fatebenefratelli 2. The chapel was taken over by the Fatebenefratelli in 1988, but is now deconsecrated.
On 2 November, All Souls Day, the Fatebenefratelli and the Orto Confraternity hold a joint procession and prayer liturgy for all those suffering a sudden death in accident, war or natural disaster. This involves Mass at San Giovanni Calibita, followed by a procession to the southern tip of the island and the throwing of a wreath into the river.
The entrance of the chapel is the door with a vertical ellipse above it, on the north side of the piazza in front of the basilica. At certain times it was possible to visit the crypt, notably on 2 November, but this seems not now to be the case.
A description of the chapel itself has not been found.
What the chapel is famous for is, of course, its crypt. It contains piles of disarticulated skulls and bones, arranged on shelves and in arched niches in some order. Some bones have been wired together to form what look like chandeliers. There is also an odd little oratory with two small sets of stalls facing each other in a barrel-vaulted side chamber, with a skeleton in the habit of the confraternity lying on the floor.
A very strange video is online, showing children helping to dust off the old bones. One little boy is trying to fit a jawbone back on its skull, without success.