The origins of the church are ancient, dating back to the eighth century. This is attested to by several passages in the
Liber Pontificalis, as well as archaeological excavations made by Msgr
Anton de Waal in 1888. De Waal brought to light ancient paintings dating from the 9th century, and others from the 13th-14th century There is a tradition that
Charlemagne, on the occasion of his coronation in 800, gave the relics of Peregrine of Auxerre to this church, whence its name. on a map of ancient Rome around 300 AD|300px The church was originally called
San Pellegrino in Naumachia. A
naumachia, literally "naval combat", is an artificial lake where naval battles were reenacted for an audience. The 5th century
"The Passion of Peter and Paul", recounts the crucifixion of
St Peter and adds:
"Holy men … took down his body secretly and put it under the terebinth tree near the Naumachia, in the place which is called the Vatican". The ruins of a structure were excavated in 1743, between via Alberico et via Cola di Rienzo.
Hülsen suggested that this structure, built close to the
Circus of Nero and lying north-west of the later
Mausoleum of Hadrian (today's
Castel Sant'Angelo), was the
naumachia the name of the church was referring to and gave it the name of
"Naumachia Vaticana". Subsequent excavations have helped to identify its shape, size and orientation. It was a rectangular structure with round internal and external corners, wide and, estimating from the excavations, at least long, oriented north–south.
Esther Boise van Deman identified the style of the brickwork facing the naumachia as
trajanic. In 1932
Jérôme Carcopino reported the discovery among
Fasti Ostienses of the dedication by Emperor
Trajan on 11 November 109 of a naumachia. The
"Naumachia Traiani" has been identified the Naumachia Vaticana.
Pope Paschal I (d. 824) granted the church to the monastery of
Santa Cecilia in Trastevere, and
Pope Leo IX (1002–1054) passed it on to the monastery of
Santo Stefano degli Abissini. A document in the archives of
Santa Maria in Via Lata dating from 1030 records that the church was located on land "outside the gate of Blessed Peter the Apostle, not far away from the
Leonine Wall of the city". From the thirteenth century onwards, the church belonged to the canons of
St. Peter's, who restored it in 1590. As a consequence of the 1648
Peace of Westphalia, the
Pontifical Swiss Guard lost the right to burial in the
Teutonic and Flemish Cemetery in the Vatican () that became reserved exclusively for German nationals. They also lost the use of their little chapel in the Church of
Santa Maria della Pietà in Camposanto dei Teutonici. In 1653,
Johann Rudolf Pfyffer von Altishofen, commander of the Swiss Guard, obtained from
Pope Innocent X the right to use the church of San Pellegrino with the adjoining cemetery. Von Pfyffer von Altishofen is buried in the church. In 1671,
Pope Clement X gave it to the Swiss Guard, who used it for their religious services until 1977 in combination with the church of
Santi Martino e Sebastiano degli Svizzeri. The cemetery of the Swiss is behind the church. For centuries members of the Swiss Guard were buried in the
crypt of the church. The oratory later fell into disrepair but was restored in the 19th century, when evidence of frescoes of the 9th century were found, as well as of others of the 13th and 14th centuries which include a depiction of
Christ Pantocrator. It was made the chapel of the Gendarmerie and the firefighters of Vatican City in 1977. == Architecture ==