San Melchiade is a later 20th century parish church at Via Costantiniana 19 in the Labaro suburban zone, on the right bank of the Tiber north of the Grande Raccordo Anulare (Circonvallazione Settentrionale).
The dedication is actually to Pope St Miltiades, who was reigning when the emperor Constantine gave peace to the Church in 313 (witness the name of the street) by means of the Edict of Milan. "Melchiades" is an erroneous spelling with a long pedigree, but it has been corrected in the revised Roman martyrology. The church, however, has not been renamed.
The parish was set up in 1959, and initially worshipped in the pre-existing convent church of Santa Maria Consolatrice a Labaro until it was provided with a permanent church. This was designed by Giuseppe Spina with the assistance of Calogero Benedetto, and was opened in 1976.
The architect is noted for unusual church layouts. Here, the church plan is completely asymmetrical and not easy to describe:
The plan is built up by starting with a longitudinal rectangle with one short end as the façade and the other behind the altar. Into the latter is inserted a smaller rectangle on the same major axis, which has its near short end slightly incurved. This gives the plan of the ferial chapel. The far right hand corner length of the larger rectangle, flanking this chapel, is cut back -here is a back entrance to the church.
Then, from about a third of the way down the right hand side of the larger rectangle a large semi-circle is drawn to end at its right hand far corner. This zone has what amounts to an aisle, running on a parallel arc from the bottom end to almost (but not quite) a quarter-circle.
On the other side of the larger rectangle there is another semi-circle of approximately the same size, the near end of which connects smoothly with the near side of the rectangle.
The larger rectangle with the two semi-circular areas is the main body of the church.
The church site is on the top of a rock outcrop amounting to a cliff, with the Via Monti della Valchetta at the bottom. The ancillary accommodation behind the church is actually inserted into the cliff for its upper storeys, and has a spectacular S-curved frontage (the church itself is invisible from this viewpoint, except for the far window of the ferial chapel). A higher range abuts the far side of the right hand semi-circle.
The exterior walls are in blank white concrete, rising to low parapets for the flat roof. The latter has a large domed skylight.
Vertical window strips are at the ends of the curved semi-circular walls, and also flank the ferial chapel. The latter has a horizontal window strip over its junction with the main church, and its back wall is entirely in glass. The roof of the curved right hand aisle is also in glass.
There is a stand-alone tower campanile to the right of the church. This consists of a tall, thin blade of concrete formed of slabs stacked on edge vertically, with the top slab narrower to form a step on the far side. This main structure is closely paralleled by a shorter slab blade, and it has a cross finial on top.
The frontage is asymmetrical as well, and involves a trapezoidal entrance portal with a diagonally angled wall continuing in front of the entrance to the right. This has concrete panels in horizontal rectangles of differing sizes. To the left of the entrance are two transverse vertical concrete slab walls, one behind the other in echelon and with each having a vertically rumpled right border.
The entrance lobby, with glass doors, fits in between the near left hand wall and the right hand diagonal wall. It is slightly less than half the height of the walls, and there is an open void between it and a large floating horizontal concrete canopy with an up-curved front edge. At the back of the void is a horizontal window strip looking into the church proper.
There is a bronze bas-relief portrait of the patron saint by the entrance.
The entrance lobby is elevated above the worshipping area proper, dominated by the roof. This has a large central skylight with a steel collar, and many radial steel beams giving a sunburst effect. The thin sectors in between the prominent beams are panelled in wood, and each contains a vertically inserted plank near the wall.
The floor is in white limestone, with the sanctuary raised on a platform of two levels.
The interior walls are in creamy white, and the windows are in clear glass. The fenestration behind the altar is especially striking, as the ferial chapel is behind the sanctuary and at a lower level. There is a view over the valley through its glass far end from the main church, since is separated from the sanctuary by a low screen wall.
The side walls of the chapel are panelled in horizontal rectangular concrete slabs, and its flat concrete roof is brought forward slightly over the sanctuary with an up-curved edge like the entrance canopy. Two longitudinal beams protrude from the underside of the roof along the chapel's major axis, and the front ends of these clasp the top of a large crucifix behind the altar. This crucifix has a bronze corpus.
The horizontal window strip above the ferial chapel is outwardly curved, and is one sheet of glass. Vertical window strips flank the chapel, the one on the left being wider.
The sanctuary furniture, being the altar, ambo and seating for the ministers, is in blocky limestone slabs.
The organ occupies the curved right hand aisle.
The church has a striking statue of the Madonna and Child, in copper and in a naturalistic style in which Our Lady resembles a Roman goddess. This is in the ferial chapel.
A painting of Pope St Miltiades in oils is by Renata Prizia.
According to the parish website (July 2018), Mass is celebrated in the church:
Weekdays 18:00 (19:00 in summer);
Sundays and Solemnities 10:30, 19:00.
On weekdays the Rosary is recited at 17:15 (18:15 in summer), followed by Vespers before the Mass. On Fridays the Mass is then followed by Exposition of the Blessed Sacrament.
The convent chapel of Santa Maria Consolatrice a Labaro is an external Mass centre.