Insula tiberina: on the origins of the cult of asclepius in Rome

Asclepius (Aesculapius in Latin) – the Roman counterpart of the Greek god of medicine – came to the Eternal City around 291 BCE. At that time, the Senate, hoping to contain a plague devastating the country, sent a Roman delegation to the Greek city of Epidaurus, home to the famous sanctuary of Asclepius. The Roman envoys were tasked with bringing back a statue of the deity, thereby securing his aid in the fight against the epidemic.

While there, they participated in the rituals performed at the sanctuary, during which, according to legend, one of the sacred snakes inhabiting the shrine escaped and hid aboard the delegates’ ship. Upon their return to Rome, the snake slipped away onto Tiber Island — an event interpreted as a divine sign commanding the construction of a temple there. The formal inauguration of the Aedes Aesculapii in Insula (the House of Asclepius on the Island), as the Romans called it, took place on 1 January 289 BCE, coinciding with the end of the epidemic.

The exact date construction began is unknown. The plague is said to have started in 293 BC, and the delegation and the serpent’s arrival on the island reportedly occurred during its course. The legend was most likely a later invention, and the sanctuary itself may have been under construction even before the envoys were dispatched — a highly plausible scenario, since the statue being brought to Rome would have needed a ceremonial home to be installed in.

Why a snake?

Snakes played an important role in the cult of Asclepius, owing to their place in the myth of how he acquired the knowledge to raise the dead. They entwine the famous Rod of Asclepius, still used today as a symbol of medicine, and they inhabited his sanctuaries, playing a part in several of the rituals performed there. The most used species was the Aesculapian snake (Zamenis longissimus), a non-venomous member of the colubrid family, which was ideally suited to this role precisely because it posed almost no threat.

When a city wished to establish its own aesculapium, it would send a delegation to an already existing sanctuary. In addition to participating in the rituals, the delegation would bring back a live snake. The transport of the snake to the new temple was treated as the journey of the god himself, and releasing it within the temple precinct symbolised Asclepius’s solemn taking up of residence there. It was also believed that snakes could detect places of special healing power — a notion that reportedly informed the Romans’ decision to build the sanctuary on Tiber Island.
Architecture and its symbolism

Aesculapia functioned both as places of worship and as healing institutions, fulfilling many of the requirements associated with ancient medical centres. A typical sanctuary comprised several key elements: the temple itself, housing an image of the god; rooms for medical practice; baths for ritual purification; and a space known as the abaton or enkoimeterion — a dormitory in which patients practised incubatio, a ritual of temple sleep. A distinctive feature of these sanctuaries was the presence of dogs and snakes, which inhabited them and played an active role in the healing process. The most celebrated such sanctuaries were in Epidaurus, on the island of Kos, in Athens, Corinth, and Pergamon.

The Roman sanctuary of Asclepius was given a remarkable architectural setting commemorating the legend of its founding. The island was reshaped to resemble a ship: its banks were clad in travertine forming a hull complete with bow and stern, while an obelisk was erected at the centre to represent the mast. Part of the travertine forming the stern can still be seen today at the eastern end of the island, while fragments of the obelisk are preserved in a museum in Naples. Also still visible is a relief depicting a snake coiling around the Rod of Asclepius, carved into one of the travertine blocks.

The temple did not always look so distinctive. The exact date of the remodelling is unknown, but analysis of the surviving walls suggests it likely coincided with the construction of the Fabrician Bridge (62 BC) and the Cestian Bridge (70–42 BC) — perhaps all these projects were part of a single urban development plan. This architectural illusion of a ship not only commemorated the miraculous arrival of the god in Rome, but also emphasised the singular nature of the place — an island that was at once part of the city and a refuge apart from it, where the sick could seek healing away from the overcrowded and epidemiologically hazardous city centre.

The temple today

The House of Asclepius was destroyed during the Middle Ages, and around AD 1000, at the initiative of Emperor Otto III, the Basilica of Saint Bartholomew on the Tiber Island was erected on its remains. The island also features the remains of a medieval complex with the tower of the Gaetani family, as well as a hospital run by the Brothers of Saint John of God (Fatebenefratelli). A road running through the centre of the island connects the two bridges linking it to the rest of the city. The remains of the sanctuary are still visible today, incorporated into the foundations of later buildings, and can be viewed from the promenade that runs around the island.