We will take you on a fascinating urban trek, on the trail of Phlegraean Bradyseism. Bradyseism (from the Greek βραδύς bradýs, “slow” and σεισμός seismós, “earthquake”) is a phenomenon linked to volcanism consisting of a periodic lowering (positive bradyseism) or raising (negative bradyseism) of the soil level, relatively slow on the scale of human times. We will start from the Macellum one of the most important natural indicators of the bradyseismic phenomenon. Better known as the Temple of Serapis, for the discovery of a statue with the effigy of the God, it represented the ancient commercial center of the Puteolan colony. We will continue the tour through the historic center, reaching the ancient fishermen’s dock, whose sea level is another clear evidence of Phlegraean bradyseism. We will move to the renewed promenade along the seafront of “via Napoli”, to discover the events of the ancient fortress of the Rione Terra.