The research concerns the Tiber delta area, about 3 km far from the present seacoast, where the remains of the ancient harbour of Rome are located. In 42 AD, Claudius started the construction of the harbour and Nero completed it in 64 AD. Then, the emperor Trajan went on to add a hexagonal basin to the former structure, which had gradually silted up. The imperial harbour was connected to the Tiber River and ultimately to the city of Rome through the Trajan channel. During the imperial period, most of the supplies imported from the Mediterranean provinces reached the city of Rome through Portus.This study applies detailed pollen, microcharcoal, and ostracod analyses together with radiocarbon dating to the sediments recovered from two cores drilled in the area of the Claudius harbour. The objective of the drillings was to identify morphological and environmental features of the Tiber delta dating back to the Roman period, and to characterize the landscape of the harbour.The chronological framing of the records is based on stratigraphical criteria, radiocarbon dates, historical data and on the typology of pottery fragments. Pollen, plant macroremains, and ostracod assemblages indicate that the two cores record different periods of time. The dock core shows the first phases of the harbour activities, recording first a marine and then a brackish environment. The plant landscape is typical of a coastal environment and appears rather preserved. The human presence is clear, but not of great impact. The channel core records mainly a brackish water environment and a strong human impact related to the presence of Portus, the port town. Anthropic indicators such as cultivated and synanthropic taxa as well as strong fire use/occurrence are evidence of a high human pressure increasing in the first centuries AD. © 2010 Elsevier Ltd.