Santissima Trinità della Missione is a demolished convent church at Via della Missione 2, where an annexe of the Camera dei Deputati is now situated. This institution is on the west side of the street, and it also occupies the north side of the Via degli Uffici del Vicario. The site is in the rione Colonna.
The dedication was to the Holy Trinity.
The convent (the Casa dei Preti della Missione) was originally built in 1642, using a benefaction from a French noblewoman known as Maria de Vignard, Duchess of Auguillon. The pastoral name of the Lazarists in Rome was to minister to the poor people of the Roman Campagna, and this work attracted much support from popes, cardinals and citizens. The motivation was of course charitable, but also in response to the belief that the moral quality of those under the government's authority had a bearing on the well-being of all its inhabitants. Putting it bluntly, if the shepherds of the Campagna were molesting their sheep and never going to Mass, then the resultant loss of God's grace would affect everybody living inside the city walls. The convent regarded Pope Innocent XII as their greatest benefactor, and recorded the fact in a commemorative inscription.
The church was rebuilt and reconsecrated in 1743. The architect was a priest of the congregation named Della Torre, and the greater part of the cost was borne by Cardinal Giacomo Lanfredini who was allowed to have his tomb in the church.
The convent was sequestered by the government in 1873, and later incorporated into the premises of the Camera dei Deputati or Chamber of Deputies. This is the lower legislative assembly in Italy's system of government. Much rebuilding work began at the start of the 20th century, including the bridge linking the complex with the main premises of the Camera across the street which went up in 1904. The church is on record as having been demolished for this work in 1907.
At present the complex is called the Palazzo della Missione, and it is open to the public on the morning of the first Sunday in the month (except August and September).
The Lazarist Fathers re-established themselves in the Prati, where their convent has a church with an identical dedication: Santissima Trinità della Missione in Prati.
The original convent entrance, with a broken and separated segmental pediment either side of a dedicatory plaque, is the first on the left going north up Via della Missione, just before the bridge over the street. However, this was not the entrance to the church, which was on the west side of the convent site with its apse reaching the Via di Campo Marizio.
This was a very large church compared to the size of the convent.
The convent entrance mentioned gave access to a passage leading to the south corner of the cloister, and then allong its south-west side to the church entrance. Another passage branched off this to run along the cloister's south-east side. The Nolli map of 1748 shows the two passages separated from the cloister garth by solid walls, which is very probably a mistake for two arcades. The other two sides of the cloister were unarcaded.
The church led off the north-west side of the cloister garth, from which there was an entrance into a narthex. A small apsed chamber was on either side of this, and the left hand one of the pair had the side entrance from the south-west cloister walk already mentioned. From the narthex, a single portal led into the main body of the church which was on a square plan, with the ceiling vault supported by four massive pillars creating side aisles. A further two pillasters on either side helped support the aisle vaults, and these separated three external chapels on each side. Each of these was on a circular plan, except the middle one on the left which was based on two conjoined circles.
The triumphal arch led into a large separate presbyterium on a square plan, and beyond that was a rectangular apse. This apse almost reached the Via di Campo Marzio.
The church has been listed as deconsecrated only, but in actual fact it has been demolished. The cloister garth survives as a little court. Information is lacking as to whether any of the church fabric survives in the existing buildings.
The “Inforoma” website’s page on this church puts it in the wrong place on their aerial photo.
On the right hand side, the chapels were as follows:
The second was dedicated to the Holy Family, with an altarpiece by an artist called Bottari.
The third was dedicated to St Paul, with an altarpiece depicting The Conversion of St Paul by Salvatore Monosilio.
On the left hand side, the chapels were as follows:
The first was dedicated to the Assumption of Our Lady, with an altarpiece by Monosilio.
The second, large chapel was dedicated to St Vincent de Paul, with an altarpiece by Milani.
The third was dedicated to St Philip Neri, with an altarpiece by Pietro Perotti.