Baiae was named after Baios, the navigator of Odysseus who died near the shores of the Sinus Baianus. The city overlooks the sparkling Bay of Naples and was one of the most luxurious and fashionable resort areas from Republican times through the Principate.

Prominent members of the Roman aristocracy, including Julius Caesar, Caligula and Nero built villas in Baiae, and Cleopatra was reported to have been at Baiae when Julius Caesar was murdered in 44 BCE. The villa of Marius, which was bought by Lucullus, and afterwards came into the possession of the imperial house, was the scene of the death of Tiberius.

Nero murdered his mother, Agrippina the Younger, near Baiae. Caligula built his famous bridge of boats and Claudius built a great villa for his wife, Messalina. Hadrian died there in Caesar's villa in A.D.138, and Alexander Severus erected large, buildings for his mother. Baiae never became, however, an independent town, but formed part of the territory of Cumae.