It is improperly called Temple of Serapis, because in 1750, during the excavations, it was discovered a statue of the Egyptian god Serapis whose warship spread at Pozzuoli.
This monument is a Macellum, or a market made the during Flavian age. It consist of a rectangular area, in the centre of which there is a court-
They were a monumental façade to a large semicircular place situated on the last side of the building.
The three surviving columns constitute a precious tool of recording of earthly movements (bradyseism) because, being corroded by mollusca show the level changes of the thermo mineral waters. The semicircular hall at the bottom contained the statues of Gods and of Imperial families members.
At the extremity of this side there are more over two latrines among the most elegant we have got from ancient times.
Inside the courtyard there is a Tholos, a circular building the surrounded by 16 columns Corinthians of African marble, architrave and frieze richly decorated, on whose rested a dome (cupola). On the long sides of the rectangle there are the Tabernae (shops) with ingresses on the portical and on the street.