An archaeological investigation was made of the church dedicated to San Celso, built on the line of one of the _decumani_ of the colony. The remains of numerous walls came to light below the floor of the church. Both of _opus reticulatum_ and _opus latericius_ these walls related to a number of buildings and a portico facing onto the _decumanus_. The brick built portico must have been covered by a barrel vault. A stair opened in its north wall, inserted between two _opus reticulatum_ walls, which must have led to the first storey of a building of Augustan date, destroyed by the construction of the church. The cement make up for the road was uncovered in which a cut was identified containing a lead _fistula_. This bore an inscription, no earlier than the 3rd century A.D., relating to the _vir clarissimus_ Acilius Glabrio and the _clarissima femina Maecia Praetextata_, probably to be linked to one _M. Maecius Memmius Furius Baburius Caecilianus Placidus, vir clarissimus_, consul in 343 A.D. and patron of Puteoli. Another _fistula aquaria_ from the Flegrean area can also be linked to this individual. Therefore, this was a _gens_ which, like the _Marii_ of _Herculaneum_, owned a workshop for lead working. Moreover, the pottery finds provided a _terminus post quem_ which indicated that this sector of the acropolis was abandoned during the second half of the 3rd century A.D.