Powerful guardian of the most sacred place in the city, for almost 2,000 years, Castel Sant'Angelo has towered over the Tiber, first as a symbol of Rome's imperial power, later as papal fortress.
The stones that form it tell a story of stratification, transformation and fascinating events that have occurred over the centuries.
It was built in 123 AD by Emperor Hadrian as a monumental tomb for himself and his family. The land on which it was built had been used for burial purposes since ancient times and was in a favorable position next to the river.
It was connected to land by a bridge named "Helius", one of the names given to the emperor. But Hadrian died before the construction was finished and the emperor Antoninus Pius was the one who completed it and used it as sepulchre for his family members, of which his son, emperor Caracalla, was the most famous.
The monument consisted of three blocks, one on top of the other, and must have been an imposing sight. On its summit was a statue of Hadrian, dressed as the sun god, driving a bronze four-horse chariot. The whole gigantic building was covered with precious marble and statues.
In the Middle Ages, its function changed totally: the enormous mausoleum was transformed into a fortress and over the next 10 centuries modified many times.
During that era, it was a fairly common defensive technique to reuse Roman monuments (theaters, monumental tombs, etc.) as part of the city walls to reinforce certain portions, or as military outposts in the areas most vulnerable to enemy attack. Emperor Aurelian, in 271 AD, made it part of the new system of walls and towers around the city.
Its strategic position controlling northern access to the city made it a fundamentally important outpost, thus Castel Sant'Angelo, reinforced with extra towers and walls, became a defensive bastion during the time of the barbarian invasions, and by the Middle Ages, had already been transformed into an unassailable fortress.
Over the great terrace, the large statue of the archangel Michael, which gives the castle its name, is particularly dear to the Romans; it's a reminder of the terrible plague that hit Rome in 590 AD and, according to a legend, ended thanks to the miraculous appearance of the angel.
Pope Gregory the Great had just been elected and did all he could to end the pestilence; he entrusted salvation to prayer and processions, as was usual in those days whenever similar disasters befell the city.
Right as the faithful were passing along the Tiber, the archangel Michael appeared and landed on the castle, conceding grace and ending the plague the moment he put his sword back into its scabbard.
The Castle maintained its defensive role for centuries and its importance grew even more when the neighborhood called "Borgo" sprang up around the tomb of Saint Peter. Pope Leo III surrounded it with high walls called the Leonine walls, founding a fortified citadel around the Vatican that was ultimately completed by Pope Leo IV.
During medieval times, Rome's most powerful families fought for control over Castel Sant'Angelo up until the return of the papal court from its long sojourn in Avignon in the second half of the 1300s, when it passed permanently into the hands of the pontiffs.
Upon his return from France, Pope Urban V declared that the only guarantee of control over Rome was to give him the keys to the Castle. He defended it with a garrison of French soldiers but the population rose up against him, occupied the Castle and even tried to raze it to the ground.
Boniface IX turned it into his residence, making the unassailable fortress a symbol of the worldly power of the popes, and connected it to the outside with a drawbridge. As with all fortresses, the castle had everything necessary within its walls in case of siege: huge water cisterns, granaries, even a mill.
It also had an escape route created by the popes: the so-called "Passetto di Borgo", a secret corridor that connected it to the Leonine walls and the Vatican, a convenient passageway that guaranteed the safety of the pope in dangerous situations, something that certainly wasn't unusual in turbulent medieval Rome.
There were many popes who used it and in a hurry, too: the Borgia Pope Alexander VI used it to escape to the castle and from Charles VIII troops.
More famous was scurrying Clement VII who used it to escape the Landsknechts during the even more famous Sack of Rome in 1527, running across it, dodging a hailstorm of gunshot as no other pope had ever done before.
Castel Sant'Angelo was considered so difficult to attack that the popes decided that there was no better place to store their treasures and so created the "Hall of the Treasury", in which was placed an enormous chest.
This gigantic safe was built directly inside the treasury room and was made much larger than the doorway so that possible evil-doers wouldn't be able to spirit the whole thing away out the door.
At the beginning of the 16th century, during the reign of Pope Alexander VI, the castle was completely transformed. This was when it became a powerful war machine: the Roman foundations were turned into huge bastions, the access-way over the bridge was made more secure with the construction of a round tower, and all around the walls, the waters of the Tiber were used to create a moat.
During the Renaissance, Michelangelo had a hand in making the papal apartments ever more opulent.
Finally, Bernini rendered the whole scene still more spectacular: he reinvented the bridge that connected the castle to land, that which became Sant'Angelo Bridge, and made it an obligatory passageway for the pilgrims crossing the Tiber, protected by the reassuring gaze of ten beautiful angels that carried symbols of the passion of Christ.
The presence of angels wasn't enough to wipe out the memory of the atrocities committed within the castle, however: in its courtyards, executions by decapitation were carried out and the heads of the unfortunates were hung from the parapets as a warning to the populace; in the dark, dank dungeons of the castle, the most horrible tortures imaginable were used even on illustrious names like Giordano Bruno, accused of heresy and burned at the stake in Campo de' Fiori; count Cagliostro, wizard, masonic alchemist and healer, was put more than once into prison there for scams and robberies during his rather adventurous life, finally being closed up inside Castel Sant'Angelo on accusations of heresy.
The only one who managed to escape the fortress was Benvenuto Cellini, goldsmith, sculptor and writer, imprisoned for having supposedly stolen goods from the pope, breaking his leg during the escape.
Even music has celebrated the monument: Castel Sant'Angelo is the scene of the tragic epilogue of Giacomo Puccini's "Tosca", in which the protagonist, wild with pain for the loss of her lover and chased by the guards, throws herself from the castle walls.
Whoever comes to Rome today and makes their way towards the Vatican, can't help but raise their eyes to admire this astounding work that has changed over the centuries and that no longer needs to defend itself; the reassuring presence of the angel on the highest terrace, with clothes and hair moved by the wind, still watches over and protects the city.
Bridge of Castel St. Angelo
One of the most famous bridge in Rome, built in the 239 AD. Large number of medieval pilgrims making their way to St. Peter's walked along it to cross the Tiber at Ponte sant'Angelo (with its Bernini Angels). Of the businesses sprang up to try to part the pilgrims from their money, the most enduring was the selling of rosaries, and the near street is still named after the rosaries (Via dei Coronari).
The street followed the course of the ancient Roman Via Recta (straight street) which originally ran from today's Piazza Colonna to the Tiber. Making one's way through the vast trongh of people in Via dei Coronari could be extremely hazardous.
In the Holy Year of 1450, some 200 pilgrims died, crushed by the crowds or drowned in the Tiber. Following the tragedy, Pope Nicholas V demolished the Roman triumphal arch that stood at the entrance to Ponte Sant'Angelo.
In the late 15th century, Pope Sixtus IV encouraged of private houses and palaces along the street. Although the rosary seller have been replaced by antiques dealers, the street still has many original buildings from the 15th and 16th century. One of the earliest, at Nos. 156-7, is known as the House of Fiammetta, the mistress of Cesare Borgia.