Sant' Agata in Trastevere is an 18th century confraternity church containing a little older fabric, which is located near the basilica of San Crisogono in Trastevere. The postal address is Largo San Giovanni di Matha 91. Picture of the church at Wikimedia Commons are here.
The dedication is to the martyr St Agatha.
The origins of the church are uncertain, but it was probably one of the many small parish churches built for the city after its emergence from the horrors of the Pornocracy at the end of the 10th century.
The developed tradition is that it dates the pontificate of Pope Gregory II (715–731), who founded a church and monastery dedicated to St Agatha. A plaque by the corridor leading to the sacristy states that this complex was established in his family home on the site in 727. However, the problem with this is that it is historically unknown as to which church dedicated to St Agatha this refers to and the suspicion is that it was Sant'Agata dei Goti. There used to be four other churches dedicated to the saint as well, all lost before the end of the Middle Ages.
Until 1575, it remained a parish church. But the policy of founding small parishes with little churches, which was followed in the early Middle Ages, led to problems when parishes became too small and poor to support their church buildings. During the centuries after 1200, the parish churches of the city were reduced in number by being either closed or converted to other uses. This one, after the parish was suppressed, was granted to the Confraternity of Christian Doctrine which used it as a a centre of their pastoral activities in Trastevere.
The church was restored by Giacomo Recalcati in 1710, a work which amounted to a rebuilding although there is evidence of mediaeval fabric in the building. It was restored again on the orders of Pope Pius VII in 1820–1821.
In 1911, it was granted to the Archconfraternity of the Most Holy Sacrament and Our Lady of Carmel, which belongs to the parish of San Crisogono. They used to have their own oratory of Santa Maria del Carmine in Trastevere opposite San Crisogono, but that was demolished in 1880 for the building of the Viale di Trastevere. The goal of the archconfraternity is to promote the cult of Our Lady, and they have made the church the centre of Marian devotion in Trastevere.
The last restoration executed so far was carried out in 1984.
The church used to stand on its own piazza, but the block of buildings that separated this from the piazza in front of San Crisogono has been demolished. As a result, the façade is part of a much wider streetscape than the one for which it was designed.
Structurally the church comprises a nave with aisles having four bays, but the aisles are divided into chapels by blocking walls. There is an entrance bay as wide as the main nave, and at the other end a presbyterium of the same size with a shallow rectangular apse. There is one long pitched and tiled roof.
The church is hemmed in by secular-style architecture on both sides, and so the exterior is difficult to examine. However, mediaeval fabric has been reported in the side walls and in the courtyard behind the apse of the church are apparently fragments of walling dated to the 5th century.
There is no campanile.
The façade was completely rebuilt in 1710 by Recalcati, who was inspired by the designs of Francesco Borromini. It is late Baroque, rather playfully executed in a yellow ochre render with architectural details in white.
There are two storeys. The first one has six Ionic pilasters, the inner four paired and the two nearest the entrance tripletted. These support an entablature which is vertically stepped over the bunched capitals of the tripletted pilasters, and which has a prominent molded architrave. The frieze above this has a short dedicatory inscription which reads: In honorem S[anctae] Agathae V[irginis] et M[artyris] MDCCX. The cornice of the entablature protrudes strongly, and is also molded. In between the paired pilasters and the outer pilasters are three blank Baroque tablets which are rather fun; a square one below a vertical rectangular one, both containing blank panels in relief, and a little horizontal rectangular one at the top in between the pilaster capitals.
There is a single entrance, with a large doorcase. Above this is a marble tablet with a long dedicatory inscription, flanked by a pair of entablature fragments with globular tassels. Above this in turn is a rather fantastic pentagonal pediment with incurved sides -a Borrominian detail. The tympanum of this is now blank, but looks as if it once contained something.
The second storey fronts the upper part of the main nave. It sits on a plinth with six stumpy pilasters without capitals, which are above the pilasters of the first storey. This plinth is decorated with a large split and transposed elliptical segmental pediment, and in the gap between the two halves is a curvaceous four-sided motif made up of curlicues and fronds (the latter recalling the palm branch of martyrdom). The second storey itself has two pairs of doubletted Ionic pilasters flanking a large vertical elliptical window which inserts into the motif just mentioned. It has a pair of angel's wings and a little incurved gable -Borromini's sense of humour was inspiring Recalcati again.
The pilasters of this storey support a deep entablature with a pair of double-capsule shaped airholes in the frieze, and inverted pilasters above the capitals below. Over the inner pair of pilasters is a small triangular crowning pediment with a palm wreath in its tympanum, and at the top corners are two halves of a split ogee pediment in lieu of a pair of finials.
The church has a single rectangular nave, with three external chapels on each side entered through an arcade. The pillars of the latter are the ends of the blocking walls between the chapels, and have Corinthian pilasters supporting a very deep entablature which runs around the interior. There is a single barrel-vaulted ceiling over nave and presbyterium, and a pair of cantoria or singers' balconies flanking the latter.
The decorative scheme is quite cool and muted, dominated by a cream colour and with restrained stucco decoration.
The ceiling of the entrance bay was decorated by Girolamo Troppa, with the Assumption of Our Lady in the centre and angels around it. The same artist executed the frescoes in the apse, which has a separate barrel vault slightly lower than that of the main ceiling which gives a very high triumphal arch. One fresco is on this vault, and the other is on the tympanum enclosed by a molded archivolt where the back of the apse joins the vault.
The first chapel on the right has an 18th century painting of St Michael the Archangel, and also one of Pope St Pius X by Giuseppe Bevilacqua, commissioned to express the archconfraternity's gratitude to the pope who granted the church to them.
In the third chapel on the right is a painting of The Madonna of the Rosary with SS Dominic and Catherine, also by Biagio Puccini.
The church has a venerated statue of the Madonna del Carmine, Our Lady of Mount Carmel, which is a reminder that the mother church of the confraternity, San Crisogono, used to be served by Carmelite friars. The statue is also called the Madonna de Noantri, and she is the patron of Trastevere. The name noantri comes from di noi altri which roughly means "us lot", or trasteverini (as distinct from that despised mob on the other side of the river, who used to express their own contempt by accusing the trasteverini of such things as eating pollo di tetto or cats).
The statue now stands in the second chapel on the left; previously, it was in the second on the right. The story is that some fisherman found a wooden statue of Our Lady in the river after a storm in 1535, and gave it to the Carmelites at San Crisogono. However, the present statue is 19th century. It stands in a gilded metal baldacchino embellished with bronze putti of different sizes.
In the third chapel on the left is another work by Biagio Puccini, The Crucifixion. The church also has a 19th century triptych showing scenes from the life of St Joseph.
Domenico Guidi, the master mason who assisted Recalcati in rebuilding the church, is buried in the centre of the church. He died in 1728.
In 2017, an unofficial source had the church open:
Monday to Friday 16:00 to 19:00, as well as for the two weekend Masses.
Apparently Mass is celebrated at 17:00 on Saturday and Sunday.
The Madonna del Carmine is carried through the streets on 16 July, when the Festa de Noantri is celebrated in Trastevere. This feast is a tradition dating in its currect form to c. 1920, but has older roots. It is now a secular feast that incorporates religious elements. The statue of the Madonna is dressed in new embroidered clothes each year in preparation, and is brought to San Crisogono in the procession. The macchina (stretcher) that it is carried on is based on a design by Domenico Gregorini, one of the architects of Santa Croce in Gerusalemme.
Other feasts of importance are those of the Dedication of the church on 4 February, St Agatha on 5 February, St Gregory II on 13 February, the Nativity of the Blessed Virgin (Our Lady's birthday) on 8 September and the Immaculate Conception on 8 December.
Vichi, Umberto. Sant’Agata in Trastevere.
Roma : Associazione di attività culturali "Alma Roma",  31 p.