San Marco Evangelista al Campidoglio, to give the church its full name, was originally built by Pope Mark (r. 336), making it the first place of public Christian worship in the heart of Rome. However, San Marco, which is the national church of Venice, has been subsequently restored and rebuilt on several occasions. The last major reworking was completed by Cardinal Angelo Maria Quirini between 1735 and 1750.
The beautiful mosaics were added by Pope Gregory IV (r. 827-44). In the centre of the apse stands Christ, holding an open book in his left hand. It reads: EGO SVM LVX EGO SVM VITA EGO SVM RESVRRECTIO. (I am the light. I am the life. I am the resurrection.)
To the left of Christ stand Pope Gregory IV (holding a model of the church), St Mark and St Felicissimus, while to the right stand St Agnes (holding a martyr’s crown), St Agapetus and Pope St Mark (r.336). The divine hand of God the Father can be seen above the head of Christ, while under his feet we see a dove with a halo perching on the edge of a fountain.
In the centre of the lower band stands the Agnus Dei (Lamb of God) flanked by twelve sheep (symbolising the twelve apostles). On the outside of the arch are roundels of Christ and symbols of the four evangelists. The two full-length figures depict St Paul and St Peter.
The nave ceiling (1465-68) bears the coat of arms of Pope Paul II (r. 1464-1471). The work of Giovannino and Marco de' Dolci, it is one of only two 15th century wooden ceilings to survive in a Roman church; the other is at Santa Maria Maggiore.
The beautiful sculpture of St Mark (and lion), above the entrance to the church, is attributed to Isaia da Pisa (active 1447-64).
The large stucco reliefs (in the nave and sanctuary) depict the twelve apostles and were executed by a variety of artists in the 1740s.
The church of San Marco is home to a fine collection of funerary monuments, most of which date back to the 18th century.