Sala della Biblioteca

You arrive at the Biblioteca through the Corridoio Pompeiano, a narrow passage decorated in the antiquarian taste of the late Renaissance. The corridor opens directly into the room. The first thing that pulls the eye is the vault.

On the eastern wall, opposite the entrance, sits the great fireplace. Above it, two monumental allegorical figures — the Church and Rome — flank the Farnese papal coat of arms at the centre. The pairing is deliberate: in this room, papal authority and Roman heritage are presented as two sides of the same idea.

Below the vault, two continuous friezes circle the entire room. The lower one is in stucco relief; the upper one is painted. Between them, the walls are punctuated by stucco medallions at the centre of each side.

The ceiling itself is divided into five concentric registers, with grotesques against a white ground alternating with ten figurative scenes from the history of ancient Rome. At the short ends of the room are portraits of Saint Michael the Archangel — the patron of the castle — and the Emperor Hadrian, builder of the original mausoleum.

The two figures at the short ends are not decoration. They are a thesis statement about the building itself: Hadrian is the origin, Michael is the protection. Everything in between — emperors, popes, treasure, prison — happens under that frame.

The name is modern. It does not appear in any sixteenth-century document.

Through the Renaissance, the room was simply the principal hall of the north wing of the papal apartment — a representation room, used for audiences and receptions, not a deposit of books. It acquired the name Biblioteca only in the twentieth century, and the reason is purely topographical: the next room over, the Sala del Tesoro, kept books, registers and documents.

In particular, the Sala del Tesoro held part of the Archivum Arcis, the papal archive of the castle. Wooden cabinets along its walls, sealed with iron locks, contained registers, briefs and bulls. Adjacent storage cabinets in the rooms above — including the Sala Rotonda — were added under Clement VIII to expand the holding.

By the twentieth century, when the castle had become a museum and the rooms needed names that visitors could find on a map, “Library” was the closest available label for the antechamber to all of that. It stuck.

The painter responsible for the entire decorative scheme was Luzio Luzi of Todi, sometimes called Luzio Romano — the same artist who frescoed the Cagliostra upstairs. He had trained alongside Perin del Vaga and was the lead specialist in grottesche working on the Farnese site.

Documentary records of payments to Luzi for stuccatura, pittura et indoratura work in this room are dated to 1544 and continue through 1545, in parallel with payments for the Loggia of Paul III and the Cagliostra.

The vault, register by register

The vault is organised in five concentric registers, framed above and below by two continuous friezes:

• The lower frieze consists of twenty-eight relief lunettes in stucco, alternating pagan scenes — sacrifices, ancient deities — with Farnese heraldic emblems.
• The upper frieze, painted, runs slightly higher and is populated with sea creatures. Stucco medallions interrupt it at the centre of each wall.
• The vault itself, divided into its five concentric registers, alternates grotesque ornament against a white ground with ten Histories of Ancient Rome.

The grotesques are not random ornament. They are quotations — the late Renaissance vocabulary of antique-style decoration that Roman painters had been studying since the rediscovery of Nero's Domus Aurea in the late fifteenth century. By 1544 the style was no longer a curiosity: it was the standard idiom for prestige rooms in the papal court.

The centre of the vault

At the centre of the ceiling, the Farnese coat of arms is flanked by two emblems: the Virgin with the Unicorn and the Lily of Justice. Both were personal devices of Paul III, painted onto the vault as a signature of the patron.

The room next to the Biblioteca, the Sala del Tesoro, was the working strongroom of the Papal States.

From the mid-fifteenth century onwards, popes used Castel Sant'Angelo as a fortified treasury and archive. By the late sixteenth century, the Sala del Tesoro housed the so-called Sanction Treasury — a reserve fund secured by six locks held by the Treasurer and the Cardinal Dean — alongside large iron chests installed by Pope Sixtus V in 1586.

Equally important were the papal archives: registers, bulls, briefs, contracts. Part of what would later be called the Archivio Segreto Vaticano was kept here for centuries. Under Clement VIII, additional storage cabinets were installed in the Sala Rotonda directly above, accessed through a narrow Roman stair that starts in the Biblioteca itself.

The contents of these archives were transferred to the Vatican between the late eighteenth and early nineteenth centuries, after the disruption of the French occupation of Rome. What remains in the Tesoro today are the original wooden cabinets and the iron chests — an empty vault that still says everything about the building's function.

From the visitor's point of view, the result is unusual. The Biblioteca is the antechamber to a vault. You read its decoration as a Renaissance representation room; you read its position in the floor plan as a security perimeter.

The Sala della Biblioteca is a node, not a destination. From it, four other rooms are accessible:

• The Sala dell'Adrianeo — a small chamber decorated with views of ancient Roman monuments (the Mausoleum of Hadrian itself among them) and scenes from the Dionysian world. Frescoes by Luzio Luzi's workshop, 1544–1545.
• The Sala dei Festoni — named for its painted festoons of fruit and flowers. Decorated under Paul III and reworked in the early twentieth century by Duilio Cambellotti.
• The Sala del Tesoro — the strongroom and archive described above, with its original iron chests.
• The Cagliostra — the small upper apartment that was walled up in the eighteenth century to become a luxury cell of the Inquisition. Entrance is on the right side of the Biblioteca. Read the full article on the Cagliostra.

A narrow Roman stair at the back of the Biblioteca leads up to the Sala Rotonda directly above the Sala del Tesoro. This is the route to the upper levels and, eventually, to the Terrace of the Angel at the top of the castle.

The Biblioteca is on Level 3 of the castle, at the northern end of the papal apartments.

From the entrance, the most direct route follows the standard visiting circuit:

1. Through the Dromos and the Atrium at ground level.
2. Up the helical ramp of Hadrian and across the diametral ramp.
3. Past the Sala delle Urne, the original burial chamber.
4. Up the stairs of the Cortile dell'Angelo to the Loggia of Julius II.
5. Across the Sala Paolina and along the Corridoio Pompeiano.
6. The corridor opens directly into the Sala della Biblioteca.

Opening hours

The Sala della Biblioteca follows the general opening hours of the National Museum of Castel Sant'Angelo: Tuesday to Sunday, 9:00 to 19:30, with last admission at 18:00. Closed on Mondays, 1 January and 25 December.

The room is part of the standard museum route. The entrance ticket gives access — no separate booking is required, and no official guide is needed. The Biblioteca is also occasionally used for cultural events, including the Sotto l'Angelo di Castello performance series, during which access may be restricted or controlled.

For the current status before your visit, see the opening hours page or check the official Direzione Musei Nazionali di Roma and CoopCulture websites.