Castel Sant'Angelo's history begins in 135 AD, when the Roman Emperor Hadrian commissioned it as a grand mausoleum for himself and his family. Completed in 139 AD after his death, the colossal cylindrical tomb housed the ashes of emperors up to Caracalla in 217 AD. Its transformation from an imperial tomb to the fortress we see today is a story intertwined with the history of Rome itself.
Hadrian's Mausoleum: The Imperial Tomb
Emperor Hadrian (reigned 117–138 AD) planned his own resting place to be a monumental tomb on the right bank of the Tiber River. Construction began around 135 AD and was completed by his successor, Antoninus Pius, in 139 AD. Hadrian's ashes were placed here a year after his death in 138 AD. The structure, originally known as the Hadrianeum, was a decorated cylinder topped with a garden and a bronze quadriga (a four-horse chariot). It served as the burial place for subsequent emperors and their families for over 70 years.
A Fortress for Popes: The Medieval Transformation
The building's function changed dramatically with the decline of the Roman Empire. In 401 AD, it was incorporated into the Aurelian Walls by Emperor Honorius to serve as a defensive bastion for the city. Much of its original marble and statuary was lost during this period and in subsequent sieges, such as the Gothic War in 537 AD when defenders hurled statues down onto attackers.
The fortress acquired its current name in 590 AD. According to legend, Pope Gregory the Great led a procession to pray for an end to a devastating plague and had a vision of the Archangel Michael sheathing his sword atop the mausoleum. This was seen as a sign that the plague would end, and the building was renamed Castel Sant'Angelo (Castle of the Holy Angel).
The Papal Refuge and the Passetto di Borgo
Throughout the Middle Ages, the castle became a critical stronghold for the papacy. In the 14th century, popes converted it into a residence and castle. Its strategic importance was cemented in 1277 when Pope Nicholas III commissioned the Passetto di Borgo, an 800-metre-long fortified corridor linking the castle directly to St. Peter's Basilica and the Vatican. This escape route proved vital during times of crisis.
- 1527: During the Sack of Rome, Pope Clement VII used the Passetto to flee to the safety of the castle from the mutinous troops of Holy Roman Emperor Charles V. He was besieged inside for months.
- Papal Apartments: Over the centuries, lavish papal apartments were built and decorated within the fortress walls to ensure a suitable residence during sieges.
- Prison and Executions: The castle was also used as a prison for high-profile inmates, including the artist Benvenuto Cellini and the philosopher Giordano Bruno. Executions were carried out in a small internal courtyard.
From Barracks to Museum: The Modern Era
After the unification of Italy in 1870, Castel Sant'Angelo's role as a papal fortress ended. It was briefly used as military barracks and a prison before being decommissioned in 1901. Following restoration work, the state opened it to the public as the Museo Nazionale di Castel Sant'Angelo in 1925. Today, visitors can explore its layered history, from the Roman burial chamber to the Renaissance papal apartments and the panoramic terrace offering stunning views of Rome. You can explore this incredible history for yourself when you book tickets to visit.
Frequently asked questions
What was Castel Sant'Angelo originally built for?
Castel Sant'Angelo was originally commissioned by the Roman Emperor Hadrian between 135 and 139 AD to serve as a mausoleum for himself and his family.
Why is it called Castel Sant'Angelo?
The name comes from a legend dating to 590 AD, when Pope Gregory the Great had a vision of the Archangel Michael sheathing his sword atop the building, signifying the end of a plague. The name means Castle of the Holy Angel.
What is the secret passage at Castel Sant'Angelo?
The "secret passage" is the Passetto di Borgo, a fortified corridor built in 1277 that connects Castel Sant'Angelo to the Vatican. It served as an escape route for popes, most famously for Pope Clement VII during the 1527 Sack of Rome.
Who is buried in Castel Sant'Angelo?
Originally, it was the tomb for Emperor Hadrian and his wife Sabina. Subsequent emperors were also interred there, including Antoninus Pius, Marcus Aurelius, and Caracalla, who was the last emperor to be buried in the mausoleum in 217 AD.
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