Castel Sant’Angelo History | Detailed Timeline, Architecture & Facts
Built around 139 AD as Emperor Hadrian's mausoleum, Castel Sant'Angelo in Rome has played numerous historical roles over centuries, serving as a fortress in 401, a papal residence in the 14th century, and a prison before becoming a museum in 1901.
Castel Sant’Angelo History Explained

Mausoleum of Hadrian
(135-139 AD)
The Castel Sant'Angelo, originally known as the Mausoleum of Hadrian, was built between 123 and 139 AD under the direction of the architect Decrianus. It was designed as a mausoleum for Emperor Hadrian and his family, inspired by the Mausoleum of Augustus. The original mausoleum consisted of a square base and a cylindrical building, with a tower containing three burial chambers. After Hadrian's death, the mausoleum became the final resting place for several emperors and their families.
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Transformation into a Fortress
(500-590 AD)
In the 5th century AD, the Mausoleum of Hadrian underwent a significant transformation. Due to the shifting political and security needs of Rome during a tumultuous period of decline and invasions, the mausoleum was converted into a military fortress. Emperor Honorius played a crucial role in this transformation by incorporating the building into the Aurelian Walls, enhancing Rome's defensive capabilities. This fortified structure, which would later be known as Castellum Crescentii in the Middle Ages, successfully protected the Vatican from the Vandals of Genseric's plundering in 455 AD. By the early 6th century, the building had taken on another role as a state prison, utilized by Theodoric.

Papal Residence and Prison
(590-1527 AD)
In 590 AD, during a plague, Pope Gregory I had a vision of the archangel Michael sheathing his sword over the castle, signifying the end of the plague. This incident gave the structure its modern name, Castel Sant'Angelo. Throughout the Middle Ages, the castle served as a refuge in times of trouble, especially for the popes, who could reach it from the Lateran through a protected passage.
Popes transformed it into a residence and refuge, fortifying it against external threats. It was also used as a prison for political prisoners. The most famous prisoner was the Italian adventurer Benvenuto Cellini.

Renaissance and Baroque Additions
(1492-1789)
In the 16th century, under Pope Paul III, the castle underwent significant renovations. Antonio da Sangallo the Younger added a cylindrical bastion, and later architects including Michelangelo, Giacomo Della Porta, and Bernini made additional modifications, such as the Passetto di Borgo, a secret passage connecting the Vatican to the castle.

Modern Use and Museum
(1789-present)
After the unification of Italy in the 19th century, the castle was used as a barracks and military prison. In 1901, it was officially designated as a national monument and turned into a museum, showcasing its rich history and displaying various artworks and artifacts. Today, visitors can explore its battlements, and underground passages, and enjoy panoramic views of Rome from the terrace.
Detailed Castel Sant'Angelo TimingsConstruction of Castel Sant'Angelo

The Castel Sant'Angelo, originally known as the Mausoleum of Hadrian, was constructed between 123 and 139 AD. The project was led by the architect Demetriano, under the orders of Emperor Hadrian.
The architectural style was inspired by the Mausoleum of Augustus but with larger dimensions. The original structure featured decorated a cylindrical edifice, with a garden and a golden quadriga (a chariot drawn by four horses side by side) at the top. The cylindrical design is an echo of Etruscan tumuli and combines elements from different architectural backgrounds. The exterior of the mausoleum was lined with marble. At the top, where the statue of the archangel now stands, there was likely a bronze statue of Emperor Hadrian depicted as a sun god. The monument was surrounded by statues, the most intact of which is the famous Barberini Faun. The construction of this iconic structure represents a significant period in Roman architectural history.
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Frequently Asked Questions About the Castel Sant’Angelo History
The history of Castel Sant'Angelo is significant in reflecting the diverse historical phases of Rome, from the imperial age to the Middle Ages, and from the Renaissance to modern times. Initially a mausoleum for Emperor Hadrian, it later served as a fortress and castle, and then became a prison and place of execution. Today, it is a museum and a testament to the city's rich history.
Castel Sant'Angelo, also known as the Mausoleum of Hadrian, was initially constructed between 134–139 AD, making it over 1880 years old as of 2023.
The initial construction of Castel Sant'Angelo, when it was still the Mausoleum of Hadrian, took about five years from 134–139 AD. However, the structure underwent several renovations and additions over the centuries, extending its construction period.
The Castel Sant'Angelo was created during the reign of Emperor Hadrian, a time of relative peace and prosperity in the Roman Empire known as the Pax Romana. It was initially built as a mausoleum for Hadrian and his family, indicating the grandeur and opulence of imperial Rome at the time.
The Castel Sant'Angelo was initially built under the orders of Emperor Hadrian as a mausoleum for himself and his family. The original structure was designed by the architect Demetriano.
The Castel Sant'Angelo exhibits a mix of architectural styles due to its long history of construction, alteration, and use. Its core structure, the Mausoleum of Hadrian, was built in the Roman architectural style with a cylindrical form, while later modifications added elements of medieval military architecture, Renaissance features, and Baroque elements.
Numerous significant events have shaped the history of Castel Sant'Angelo. It has served as a mausoleum, a military fortress, a papal residence, and a prison. One of the most famous incidents was in 590 AD when Pope Gregory the Great saw a vision of the Archangel Michael sheathing his sword atop the castle, signifying the end of a plague, leading to its present name.
Castel Sant'Angelo has significantly contributed to Rome's cultural heritage as a prominent symbol of the city's history and evolution. Its architectural style, historical use, and the many stories it holds contribute to the rich tapestry of Rome's history. As a museum, it provides insights into Rome's past for both residents and tourists.
Some lesser-known facts about Castel Sant'Angelo include its use as a hiding place for Popes during sieges due to a secret passage called Passetto di Borgo connecting it to Vatican City. The castle also contains a historical prison where many notable prisoners were held, including the sculptor and goldsmith Benvenuto Cellini.
Yes, there are guided tours available that offer a comprehensive explanation of the history of Castel Sant'Angelo. These tours often include insights into the architectural styles, historical events associated with the castle, and stories about its famous inhabitants. It is recommended to book guided tours online for seamless access to the castle at the time of visit.