What Mummius had casually referred to as the baths was in fact an impressive installation within the house that seemed to have been built over a natural terrace on the side of the hill, facing the bay. A great coffered dome lacquered with gold paint arched over the space, pierced by a round hole at the summit that admitted a beam of pure white light. Beneath this was a round pool with concentric steps leading into its depths, its surface obscured by roiling masses of sulphurous steam. An archway on the eastern side opened onto a terrace furnished with tables and chairs, with a view of the bay. A series of doors around the pool defined a semicircular arcade; the doors were of wood painted dark red, the handles were of gold in the shape of fish with their heads and tails attached to the wood. The first door led into a heated changing room; the other rooms, so Mummius explained as we shed our tunics, contained pools of various sizes and shapes, filled with water of various temperatures.

'Built by the famous Sergius Orata himself,' Mummius boasted. 'You've heard of him?'

'No.'

'The most famous Puteolian of all, the man who made Baiae what it is today. He started the oyster farms on Lake Lucrinus – that earned him his first fortune. Then he turned out to be a master engineer at building pools and fish ponds, and villa owners all around the Cup showered him with commissions. This house contained a modest bath when Crassus acquired the estate. With Crassus's permission, not to mention Crassus's money, Lucius Licinius added an upper storey here, a new wing there, and had the baths completely rebuilt, employing Sergius Orata himself to draw up and execute the plans. I'd prefer a little grotto in the woods or a common city pool myself – this kind of luxury is rather absurd, isn't it? Impressive but excessive, as the philosophers say.'