Santi Martino e Sebastiano degli Svizzeri is a tiny 16th century confraternity church on the Largo di San Martino, up against the north colonnade of the Piazza di San Pietro and within the territory of Vatican City. Picture of the church on Wikimedia Commons is here. There is an English Wikipedia page here.
The dedication chosen was to two famous saints who had been soldiers.
Before 1648, the Swiss Guards had burial rights at Santa Maria della Pietà in Camposanto together with other expatriate subjects of the Holy Roman Empire. However, the Treaty of Westphalia in that year excluded Switzerland from the Empire -and so the Guards lost their rights here. As a result, they were granted possession of the nearby church of San Pellegrino in Vaticano in 1671 because it had a cemetery and a burial crypt.
The Nolli map of 1748 shows a small rectangular edifice facing east to west, with an entrance facing east. There must have been a major restoration some time after this, because the orientation of the church was rotated with a new façade facing south.
There was a restoration on the creation of Vatican City as an independent state in 1929, and another one in 1965.
The Swiss Guards had charge of the two churches until 1977, this one as the preferred place of worship and San Pellegrino as a mortuary chapel. In that year, the latter was given to the Gendarmerie instead.
In 1999, there was a major restoration and a re-ordering. The orientation before then was from south to north, but this was rotated so that the church is now oriented west to east. This, in fact, is the reverse of the original orientation of the 16th century church -as mentioned above.
The church has a trapezoidal plan externally, because the back wall (before 1999) is the Leonine Wall, and this is at about seventy degrees to the right hand side wall. To the west is the orginal chaplain's house, forming one block with the church. However, the latter has its own pitched and tiled roof.
There is a little bellcote or campanile over the right hand side wall, with a space for a single bell.
The former façade, now the right hand side wall but keeping the entrance, looks 18th century.
There are four large Doric pilasters supporting an entablature without an inscription. Above this is a shrunken pediment which does not occupy the entire roofline. The tympanum of the pediment has the coat-of-arms of Pope Pius V (allegedly).
The molded doorcase is surmounted by its own triangular pediment over a short inscription Pius V Pont. Max., and there is a large round window with a molded frame above that.
Prior to 1999Edit
The church's interior has no online presence. The following is taken from its English Wikipedia page:
"The chapel was decorated with frescoes by Giulio Mazzoni, a pupil of Vasari. These frescoes were renovated in the years 1727–1728 by Carlo Roncelli, and were finally removed in 1967 for conservation purposes and stored in the Vatican Museums.
The frescoes over the altar represent God the Father, while in the right-hand niche is St. Sebastian, and in the left one St. Martin. The altarpiece represents the Annunciation of the Virgin Mary. On the right wall, near the altar, Jesus Christ is depicted on the cross, surrounded by St. Peter and St. John the Evangelist; on the left is the Virgin Mary with St. Anne and the child Jesus.
The entrance now leads into the church with the sanctuary on the right. Over the entrance is a new choir gallery with a bronze balustrade. The original sanctuary apse straight ahead, now occupying the left hand side wall of the church, contains the organ.
The nave roof is a so-called pavilion vault, which is a cross-vault with the sectors coved (concave). The decorative scheme of the ceiling and walls is very simple, in white and a faint pink respectively.
The new altar is simple, in Carrara marble. The tabernacle is in the form of a sun with rays, accompanied by a pair of adoring angels looking down from above. Over these is a large crucifix. These works are in bronze, and the set includes a ciborium and monstrance. Together with the choir balustrade and the bronze door to the separate baptistry, they comprise a commission given to Gino Giannetti in 1999.
The above-mentioned door is to the left, opposite the sanctuary, and next to it is a stained glass window containing the Stations of the Cross designed by Trento Longaretti. Two other windows are also by him, depicting The Annunciation and Pentecost.
The Swiss Guards have much to endure from tourists, and hence they probably wish to keep their church private and free from casual visitors. In any case, it is within the security cordon of Vatican City which a permit is required to penetrate.
Those seriously interested in visiting, preferably with academic credentials, may try contacting the Pontifical Swiss Guard Command.
The church can be visited by pilgrim groups from Switzerland, but arrangements have to be made beforehand.
The exterior is visible from the colonnade. The church is located on a small triangular piazza sandwiched between the colonnade and the wall of the Palazzo Apostolico, which here is part of the original wall of the Leonine City.