A trench excavated inside the Roman cryptoporticus produced important data regarding the post-classical occupation of the town. This structure, now completely below ground, is one of ancient Allifae’s surviving monuments. The trench was positioned in the south-eastern arm of the _cryptoporticus_, close to one of the cuniculi which gave access to the structure. The excavation aimed to evaluate the nature of the stratigraphic sequence and the soil covering the monument, as well as to uncover the original floor level. The pavement was reached at a depth of circa 3.60 m below the top of the vault’s extrados, therefore at circa 1.55 m below present ground level. It was covered by a series of strata and occupation layers that, despite the partial excavation of the building in the 1960s, resulted as being homogeneous and only slightly contaminated. The stratigraphic data showed continuity of use into the late antique or early medieval period. The ground level was then raised by a series of medieval occupation layers.