November
29 – Saint Saturninus of Rome
Chapel of Saint Saturninus in Santi Giovanni e Paolo in Rome – see also
30 – Saint Andrew
In Rome, you can visit the church of Sant’Andrea della Valle, which is a Baroque structure dedicated to Saint Andrew, and a painted cycle by Mattia Preti wraps around the apse. It shows the raising of the cross, the Crucifixion, and then the taking down of the cross. You can take “virtual tour” here.
December
2 – Saint Bibiana
Santa Bibiana in Rome: Location – Photographs – Statue of Saint Bibiana by Bernini – Description
3 – Saint Francis Xavier
San Francesco Saverio del Caravita in Rome
5 – Saint Sabas
The church of the monastery of San Saba in Rome was founded in the seventh century by monks from Mar Saba fleeing invaders from the east. Enjoy this photo album. You can read more about the church at the excellent Churches of Rome Wiki (now hosted by Fandom).
23 – Saint Servulus
Death of San Servolo by Tommaso Chiari in the nave of San Clemente (this a preparatory sketch, info here and here)
25 – Saint Anastasia
The Church of Sant’Anastasia in Rome
26 – Saint Stephen
The Church of San Stefano Rotondo on the Caelian Hill in Rome dates to the 5th century and is the station for this day of the Christmas stational liturgy. The Church of San Lorenzo fuori le mura in Rome claims his relics. There is a 13th century fresco cycle in the porch, but they are much restored and inaccessible virtually.
31 – Saint Sylvester
A chapel dedicated to Saint Sylvester in the church of Santi Quattro Coronati in Rome preserves a vividly colored fresco cycle dating to the thirteenth century. The cycle depicts stories that were fabricated several centuries after his lifetime. Information – photos, scroll down past photographs from San Clemente to see the photographs from the chapel of Saint Sylvester – video
January
16 – Saint Marcellus
The church of San Marcello al Corso in Rome – info, photos.
18 – Cathedra Petri
The Cathedra Petri in the Basilica of San Pietro in Vaticano (more here and here).
18 – Saint Prisca
The Church of Santa Prisca in Rome
20 – Saint Sebastian
The church of San Sebastiano fuori le mura in Rome
21 – Saint Agnes
Sant’Agnese fuori le mura, especially its apse mosaic (Photo gallery).
23 – Saint Emerentiana
Coemeterium Maius or Catacombe di Sant’Emerenziana
The Chapel of Saint Emerentiana in the Church of Sant’Agnese fuori le mura
The Chapel of Saint Emerentiana in the Church of Sant’Agnese in Agone
30 – Saint Martina
The Church of Santi Luca e Martina in Rome
February
5 February – Saint Agatha
Sant’Agata dei Goti in Rome
Sant’Agata in Trastevere, also in Rome
10 February – Saint Soteris
On the place of her burial in Rome
March
9 – Saint Frances of Rome
Santa Francesca Romana in Rome, on the Roman forum and originally dedicated to Santa Maria Nova – Nolli Map and Photo Gallery.
10 – Forty Martyrs of Sebaste
The Oratory of the Forty Martyrs at the Church of Santa Maria Antiqua in Rome (photos)
12 – Saint Gregory the Great
San Gregorio Magno al Celio in Rome (17C Sculpture)
31 – Saint Balbina
The Church of Santa Balbina in Rome
April
9 – Saint Mary of Egypt
The Church of Santa Maria Egiziaca in Rome, a temple converted into a church. Ninth-century frescoes still cover its walls. See also (scroll down). Watch.
17 – Saint Anicetus
Chapel of Saint Anicetus in the Palazzo Altemps
25 – Saint Mark
The Church of San Marco in Rome
May
3 – The Invention of the True Cross
The church of Santa Croce in Gerusalemme in Rome
6 – Saint John before the Latin Gate
The Church of San Giovanni a Porta Latina in Rome – photo gallery
The Chapel of San Giovanni in Oleo in Rome
12 – Saints Nereus and Achilleus
The church of Santi Nereo e Achilleo in Rome
12 – Saint Pancras
The Church of San Pancrazio in Rome
13 – Saint Maria ad Martyres
Santa Maria ad Martyres in Rome
14 – Saint Boniface of Tarsus
Church if Santi Bonifacio ed Alessio in Rome
19 – Saint Pudentiana
The church of Santa Pudenziana in Rome, 11C Fresco of Saint Pudentiana
21 – Saint Constantine
Sala di Constantino in the Vatican
June
2 – Saints Marcellinus and Peter
The Catacombs of Saints Marcellinus and Peter – official website, see also, and a painting with Saints Marcellinus and Peter
9 – Saints Primus and Felicianus
The Chapel of Saints Primus and Felicianus in the church of Santo Stefano Rotondo in Rome (gallery of photos of the church, including the mosaics in the chapel, photo of the apse mosaic)
12 – Saint Onophrius
Sant’Onofrio al Gianicolo in Rome (photo gallery)
16 June – Saints Quiricus and Julitta
The Shrine to Saints Quiricus and Julitta in the Chapel of Theodotus in the church of Santa Maria Antiqua in Rome (background – video introducing the church – video of the chapel, in Italian – extensive photo gallery, and another extensive photo gallery)
26 June – Saints John and Paul
The Church of Santi Giovanni e Paolo in Rome
29 June – Saints Peter and Paul
San Pietro in Vaticano in Rome
30 June – Saint Paul
San Paolo fuori le mura in Rome
July
7 July – Saint Cyril and Methododius
The Chapel of Saints Cyril and Methodius in the lower church of San Clemente in Rome
10 July – Saints Rufina and Secunda
The Church of Sante Rufina and Secunda in Rome
17 July – Saint Alexius of Rome
Sant’Alessio all’Aventino in Rome and the Madonna di Sant’Alessio
August
1 August – Saint Peter ad Vincula
The Church of San Pietro in Vincoli
1 August – The Seven Maccabees
Fresco in Santa Maria Antiqua in Rome (description – photo – photo)
5 August – Saint Mary ad Nives
The Basilica of Santa Maria Maggiore in Rome (Smarthistory – Columbia University Art Atlas)
Founding of Santa Maria Maggiore by Masolino.
Founding of Santa Maria Maggiore by Matthias Grünewald (Web Gallery of Art)
6 August – Saint Sixtus II
Cappella Niccolina, Palazzi Pontifici, Vatican painted by Fra Angelico (see also)
10 August – Saint Laurence
San Lorenzo fuori le mura in Rome
Cappella Niccolina, Palazzi Pontifici, Vatican (see also and also)
11 August – Saint Susanna
The church of Santa Susanna in Rome
14 August – Saint Eusebius of Rome
Sant’Eusebio all’Esquilino in Rome – Glory of Saint Eusebius, Preparatory Sketch, Slideshow
29 – The Beheading of Saint John the Baptist
The Church of San Giovanni Decollato in Rome (and its painting of the Beheading)
29 – Saint Sabina
The Church of Santa Sabina in Rome
30 – Saints Felix and Adauctus
Shrine of Saints Felix ad Adauctus in the Catacomb of Commodilla
September
16 – Saint Cornelius
The Catacomb of Callixtus in Rome – Crypt of Lucina (more and also, both from a website dedicated to the name Cornelius), on the frescoes and the fresco of Saints Cornelius and Cyprian
27 – Saints Cosmas and Damian
The Church of Santi Cosma e Damiano in Rome – apse mosaic
October
5 – Saint Galla
The Church of Saint Galla Antiqua in Rome
14 – Saint Callixtus I
Catacombe di San Callisto – Official Website, Roma sotterranea: Or Some Account of the Roman Catacombs, Especially of the Cemetery of San Callisto, The Catacombs of Saint Callistus: History and Description
November
9 – Dedication of the Basilica of Saint Savior
San Giovanni in Laterano in Rome
9 – Saint Theodore
11 – Saint Martin I
13 – Saint Stanislaus Kostka
Chapel of Saint Stanislaus Kostka in Sant’Andrea in Quirinale
23 – Saint Clement
The Church of San Clemente in Rome
24 – Saint Chrysogonus