Caligula’s Palace and Bridge

Roman Emperor Caligula and the Floating Bridge of Baiae

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Roman leader Caligula is well-known for his brief stint as the emperor of Rome, from 37 AD through 41 AD. Some say that Caligula displayed signs of madness during his reign. According to historical accounts, one of these displays of madness was Caligula’s demand for the construction of a floating bridge across the Bay of Baiae so that he could ride triumphantly across it. Some historians dispute the building of this bridge. With differing accounts of exactly what happened during Caligula’s reign as emperor, we may never know whether the floating bridge of Baiae was actually constructed, but it remains a lasting story of power, madness, and what happens when the two intertwine.

A marble bust of Caligula

A marble bust of Caligula. Image source .

Caligula’s father, Germanicus, was nephew and adopted son of Tiberius, the emperor of Rome. Tiberius died in 19 AD, leaving Caligula and his mother, Agrippina, to believe that Tiberius had poisoned Germanicus due to a political rivalry. Agrippina publicly declared she would seek revenge on Tiberius, which led to her imprisonment, and the imprisonment of Caligula’s siblings. They all perished in prison, while Caligula was spared due to his young age. Caligula was left to be taken in by Tiberius, the very man who Caligula believed to be responsible for his family members’ deaths. Eventually, Caligula became the emperor of Rome, with his leadership being overshadowed by his alleged acts of madness. One of the most infamous acts of madness was his demand for the construction of a floating bridge across the Bay of Baiae.

Baiae was an integral part Portus Julius, home port of the Western Imperial Fleet of ancient Rome, and towards the end of the Roman Republic it was a fashionable resort, popular with the super-rich, and notorious for the ‘hedonistic temptations’ on offer, and for rumours of scandal and corruption.

Baiae (Baia) across the Bay of Naples

Baiae (Baia) across the Bay of Naples. Did Caligula cross this distance with a floating bridge? Credit: Wikimedia

It is said that in 39 AD, construction of the bridge began. Caligula wanted a bridge that he could ride triumphantly across it in his carriage. This idea alone seems to confirm that Caligula may have been suffering from some form of madness, as it is hard to imagine an emperor spending his time riding a carriage across a bridge with no real purpose for doing so. According to Roman historian Suetonius, the bridge spanned more than 3 miles across the bay, from the town of Baiae to the neighboring port of Puteoli. Pontoons from around the region were used to build the bridge, with sand poured over them. Caligula then draped himself in a gold cloak, donned the breastplate of Alexander the Great and crossed the bridge on his horse. The bridge was constructed to contain resting points for pauses in Caligula’s ride. These resting points also contained drinkable water.

A remaining hull from massive vessel which served as an elaborate floating palace to the emperor

A remaining hull from massive vessel which served as an elaborate floating palace to the emperor. Could this have been much like the rumored Bridge of Baiae? Credit: Wikipedia

Some say that Caligula did this in defiance of a prediction from Roman astrologer Thrasyllus. Supposedly, Thrasyllus predicted that Caligula had “no more chance of becoming emperor than of riding a horse across the Gulf of Baiae.” This may shed some light on Caligula’s reasoning for having the floating bridge constructed for his seemingly pointless activity of riding his horse across it in triumph. Maybe rather than a sign of madness, this was a boastful display over having proved Thrasyllus and other naysayers wrong. Others say that the construction of the bridge was merely Caligula’s attempts at laying the framework for his military glory.

Due to a lack of physical evidence, many historians believe that accounts of Caligula’s floating bridge are fictional stories. There is very little written evidence of Caligula’s reign to begin with. Many historians who wrote about Caligula were considered to be biased, and it remains unclear which stories are fiction, and which are fact. Some scattered remains in the area were being shown to tourists as the “Bridge of Caligula” as recently as the 18 th century. However, it cannot be confirmed that these remains are the floating bridge. With such uncertainty as to the events that occurred during Caligula’s reign, we may never be able to confirm the existence of the floating bridge. To this day, the idea of the bridge remains a symbol of Caligula’s power, whether it is viewed as a sign of his madness, a sign of his military power, or simply a sign of Caligula showing the naysayers that they were wrong, and that he would eventually become the emperor of Rome.


rbflooringinstall's picture

I like the idea of him wanting the bridge to disprove the prediction.

Peace and Love,


Ol' Tibby didn't die in 19 AD as stated here, but right before Caligula was crowned Caesar, as he was his predecessor. Just to let you know. Chears!

Caligula was not insane.
The bridge was for the solution of jammed ships and severe famine in Rome.

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