A large number of granite shafts from the Troad are preserved in Tarraco. Many of them belong to a very similar typology and size, meaning that they must have come from the same building. We propose that this was the porticus in summa cavea of the amphitheatre or more probably the portico of the representational square in the provincial forum. Furthermore, the presence of rotae from the paving of the worship hall of that forum allows us to document a restoration of this area at the same time as we attest the architectural and decorative similarities to the Templum Pacis in Rome. Analysis of these pieces also allows us to study their reuse in the early Christian and Visigothic periods, as well as the probable export of some shafts to other towns during the mediaeval period.