The commune of Bacoli is located to the south-west on the Gulf of Pozzuoli and is well-known for the ancient port, villas and spas of Baia, an imperial residence in Roman times. Today a fishermen's borough, was a Roman town with the name of Bauli.
Baiae (today Baia) was a fashionable and luxurious coastal resort, especially towards the end of the period of the Roman Republic and throughout the Empire, even more popular than Pompeii, Naples, and Capri. Famous for its medicinal warm sulfur springs, purple oysters, and mild climate, it was an ideal retreat from the heat of Rome, and many prominent Romans had villas in the area. It was at his villa near Baiae that the Emperor Hadrian died in 138 AD.
Baiae was also the location for a spectacular stunt (in AD 37) by Caligula, who on becoming Emperor ordered a temporary floating bridge to be built using ships as pontoons, stretching for over two miles from the town of Baiae to the neighboring port of Puteoli (Pozzuoli), across which he proceeded to ride his horse,to challenge an astrologer's prediction that he had "no more chance of becoming Emperor than of riding a horse across the Gulf of Baiae".