With an area three times larger than Pompeii, Baia, about 15 km from Naples and within the volcanic area of the Phlegraean fields, is the largest underwater archaeological site in the world. In 100 BC Pompeii is an ordinary city of small traders crouched on the slopes of Mt. Vesuvius, while Baia gains a peculiar reputation: it gradually becomes the ancient Las Vegas or Monte Carlo of the Roman Empire, a real posh center for noble gens and the powerful . Nestled in the center of the Gulf of Pozzuoli, Baia is flanked on one side by the port of Puteoli (ancient Pozzuoli) and on the other by the port of Capo Miseno. Both of these landings boast enormous prestige, one is the nerve center of Roman trade capable of handling a traffic of over 1,000 ships per year, with the task of supplying the capital with food but also with very precious rarities coming from the exotic east ; at the head of Miseno, on the other hand, allocates the imperial fleet to defend the interests of the entire gulf. Sumptuous buildings, monumental spas and brothels frequented by the rich "holiday makers" appear. Owning a villa here means prestige, a worldly duty. Baia is the most exclusive and renowned holiday resort in the ancient world, the fulcrum of the "dolce vita" of that time. It is no coincidence that emperors such as Caesar, Nero, Marcus Aurelius and Hadrian also decide to fix their imperial mansions there to take refuge from the austere and frenetic life of the capital. No wonder then that just in Pozzuoli an amphitheater was born long before the best known Colosseum in Rome.