Sant'Andrea a Ponte Milvio is a tiny 16th century devotional church (not an oratory) located at Via Flaminia 441, which is in the Flaminio quarter just south of the Ponte Milvio. A picture of the church on Wikimedia Commons is here.
The dedication is to St Andrew the Apostle.
Do not confuse this church with Sant'Andrea del Vignola, also on the Via Flaminia but nearer the city centre. Also, beware of the older name Sant'Andrea a Ponte Mollo after an obsolete Italian name for the bridge.
The remote orgin of the church lies in 1462, when the alleged head of St Andrew was brought to Rome. It had originally been enshrined at Patras in Greece, the traditional site of his martyrdom. This had been ruled by the Despotate of Morea, the last outpost of the Byzantine Empire, until 1460 when it was conquered by the Ottoman Turks. The last joint ruler, Thomas Palaiologos, fled with the relic and eventually settled at Rome. Cardinal Bessarion oversaw the relic's journey to Ancona, where it was taken overland to Narni and then boated down the Tiber to the Milvian Bridge. Pope Pius II came out of the city on 11 April, received the head from the cardinal at this spot and brought it back in triumph. It remained in Rome until donated to the Patriarchate of Constantinople by Pope Paul VI as an ecumenical gesture.
The pope ordered a monument to be erected here in the following year, 1463, and to it was attached a small cemetery for anonymous pilgrims who had died on pilgrimage. In 1566 the site was granted to the confraternity at Santissima Trinità dei Pellegrini, who were involved in the care of pilgrims, and they probably built the church then (although its foundation is undocumented). It functioned as a mortuary chapel, and also as a place of worship for the surrounding area which back then was almost uninhabited. The land was an overgrazed sheep-walk, with no trees, although country villas began to be built in the vicinity in this century.
In 1803 Giuseppe Valadier restored the bridge, and also repaired the church as part of the same project. The monument was destroyed by lightning in 1866, and rebuilt subsequently.
The edifice is now a subsidary church of the parish of Santa Croce a Via Flaminia, and has no pastoral function. It is apparently seldom open. The cemetery is closed to burials, but functions as a garden.
Most descriptions, in print as well as online, describe the building as an oratory. It is not; the Diocese considers it to be a church. It is perhaps the most accessible example of the kind of tiny place of worship provided for the peasants of the Campagna before the city started to sprout its suburbs.
The church is on the open space just south of the Ponte Milvio, which is known as the Piazzale Cardinale Consalvi. The church itself is on the Via Flaminia, and the walled cemetery stretches back to the Via Tiziano to the east.
The location is just north of the terminus loop of the tram from Porta del Popolo. This is tram number 2, and is an interesting way to go and see the Ponte Milvio as well as this church. The route is the oldest tram line in Rome (although not the oldest electric one), opening as a horse tram in 1877.
Despite its status as a church, it is a small nondescript rectangular building set longitudinally to the road and looks like an old farmhouse. The roof is pitched, there is a small bellcote on the roofline facing the cemetery and the walls are rendered in pink below and grey above. The main entrance, on the street frontage, is slightly trapezoidal.
The interior is very simple, with whitewashed walls and a single altar. There is an exit through to the cemetery, the wall of which attaches to the church so that you can only get into it when the church is open.
The monument is the most important thing on the site. It used to be in marble, but after its destruction by lightning was rebuilt in limestone. The statue of St Andrew shows him carrying his cross, and is now considered to be by Paolo Romano (also known as Paolo Taccone). This stands on a plinth, within an open aedicule which consists of four Ionic columns supporting a deep entablature with a projecting cornice. There is a very shallow saucer dome, which is invisible from the ground except for its stone cross finial.
The plinth carries the coat-of-arms of Pope Pius II, over a long inscription in an archaic calligraphic style. Note that the words are run together without spaces between them. This was done when writing in ancient times in order to save on valuable papyrus, but the ancient Romans would not have found it appropriate for monumental epigraphs. The inscription reads:
Pius II Pont[ifex] Max[imus], sacrum beati apostoli Andree caput ex Peloponneso advectum, his in pratis excepit et suis manibus portavit in Urbem anno salutis MCCCCLXII, pridie Idus Aprilis que tunc fuit secunda feria majoris hebdomadae. Idcirco hunc titulum erexit et universis christifidelibus qui eadem feria im posterum hunc locum visitaverint et, quinquies Christo Domino adorato, intercessionem Sancti Andree pro communi fidelium salute imploraverint, plenariam omnium peccator[um] in forma Ecclesie consueta perpetuo duraturam indulsit remissionem. Anno pont[ificatus] sui quarto.
("Pius II, great priest, in these meadows received the sacred head of the blessed apostle Andrew which had been brought from the Peloponnese and with his own hands carried it to the city in the year of savation 1462, on the day before the ides of April which then was the second day of the great [holy] week. Therefore he put up this inscription, and all Christians who visit this place on the same date in future and, adoring Christ five times, request the intercession of St Andrew for the common safety of the faithful, will be granted a complete and enduring remission of all sins, the usual conditions set by the Church having been fulfilled.")