The Temple of Serapis, dating back to Roman times (I - II century AD), is none other than the ancient Roman market (macellum) of Pozzuoli. The building was improperly called the Temple of Serapis for the discovery of a statue of the Egyptian god at the time of the first excavations. The building, brought to light in the mid-eighteenth century, under the reign of Charles III of Bourbon, is the place that more than any other, along with the ancient city of Baia, has witnessed over the centuries the phenomenon of the bradyseism of the fields Flegrei. For centuries, the columns of the Temple of Serapis have represented the most accurate metric index that was available to measure the phenomenon of the bradyseism of the Campi Flegrei. Until 1983 they were partially submerged by the sea and today they are found above the sea level. Looking at the long stem of the 3 great columns of the Serapeum, you can still see the holes of the dates of the sea (foraminifera molluscs living on the water's surface) which clearly indicate the highest level reached by sea water in the past. The base of the temple is connected with some natural underground to the sea: when bradyseism is in the passive phase, the temple disappears under several centimeters of water.
The building is similar to other Roman markets that are still preserved throughout the Mediterranean area (such as those of Rome, Timgrad, Djemila, Perge and Cremna), only that this of Pozzuoli is undoubtedly the most monumental and intact , thanks also to the bradyseismic submersion that has preserved it from a greater spoliation of its architectural elements.
The archaeological site of Serapide, built under Alexander Severus (emperor in 222-235 AD) according to the typical pattern of the markets of the Roman world, looks like a rectangular courtyard surrounded by rows of tabernae (shops) accessible from the square or the perimeter streets . Even today you can see the steps with dolphin-shaped balustrades, pink marble, friezes depicting sea monsters, columns decorated with figures of tritons and blacks that still shine among those that were the shops of traders.