San Michele Archangelo a Castel Giubileo are two former churches with the same dedication to Michael the Archangel, at the fortified farmstead known as Castel Giubileo in the district of the same name. This is on the Salita del Castel Giubileo.
The conical hill on which Castel Giubileo stands is one of a group of hills close to the left bank of the Tiber, at about the fifth milestone on the Via Salaria up to the seventh where the farmstead stands. This is the site of the ancient Etruscan settlement of Fidenae, which was an outpost of theirs on the wrong side of the river (the ancient boundary between the Etruscans and Latins was the Tiber). As a result, the archaic Romans viewed it with enmity and it features in their annals up to the 5th century BC, until they managed to capture and annex it in 435 BC. Nothing survives of its buildings.
Apart from the deadly collapse of a wooden amphitheatre in the year 27, nothing of note then happened here until the last period of imperial rule in the West.
A basilica dedicated to St Michael was built on the hill towards the end of the 4th century. The important thing about this is that it is the earliest church known to have been dedicated to him in the West, antedating the more famous sanctuary of Monte Gargano which was thought to have been the oldest. Thus, this little hill is the progenitor of the tradition in western Europe of building churches to St Michael on top of prominent hills.
The first mention of the basilica is in the so-called Martyrology of Jerome of the mid 5th century, and again in the Liber Pontificalis where Pope Symmachus was described as improving access arrangements. Pope Leo III gave a benefaction to the church at the end of the 8th century, but it seems to have been abandoned subsequently. It was the pilgrimage shrine associated with Rome furthest from the city, and hence especially vulnerable to the breakdown of law and order.
During building work at the Generalate of the Clarissan Sisters of the Blessed Sacrament at Salita del Castel Giubileo 11, foundations of the basilica were discovered and excavated in the season 1996-7. These are south of the farmstead.
The fortified farmstead came into existence possibly in the 9th century, and was orginally known as Mons Sancti Michaeli or "Mount St Michael" after the lost shrine. In 1286 it was recorded as being in the possession of the nunnery of San Ciriaco on the Corso, and the surviving fabric is of this century. The nunnery was a disgraceful institution in the later Middle Ages and it was finally suppressed as a result, but in the meantime the noble family of Giubileo gained possession of it in about 1300 and gave it their name. It passed to the Chapter of St Peter's in 1458.
There was a chapel or little church next to the entrance to the complex, which is recorded as having a vaulted ceiling. However, by the early 19th century the defensive aspect of the little castle had been forgotten and it is recorded as being merely a farm. Up to the conquest of Rome by Italy in 1870, Mass was said in the chapel in summer only for the benefit of shepherds and also for women who are recorded as coming from the city to make hay in the river meadows nearby.
More erudite tourists used to visit in order to view the site of the ancient city of Fidenae, and they have left descriptions of the spectacular view. Although there were trees around the foot of the hill in the mid 19th century, there were very few elsewhere in the surrounding countryside which was being viciously overgrazed by flocks of sheep. As a result, one could see all the way back to the city, where the domes and towers appeared on the horizon, as well as all the way to the mountains to the east and north.
This chapel seems to have been abandoned in the late 19th century, and it is now apparently a ruin. Very unfortunately, suburban development has been allowed on the hill itself as well as all around and so the view has mostly been ruined.