Today, the deltaic plain of the Francolí is highly urbanised and the delta front is completely transformed and integrated into the harbour of Tarragona. Based on an interdisciplinary approach combining new GIS and palaeoenvironmental analyses together with a review of old maps, historical, archaeological, and palaeoclimatic data, we propose to reconstruct the natural dynamics affecting the Francolí delta during the last millennia until 2020 CE. We will also explore human-nature interactions in the Francolí delta and demonstrate how they are involved in the evolution of the delta and the harbour of Tarragona for at least the last 2 millennia. These interactions contribute to shape mixed morphologies: coastlines are modified by harbour structures and part of the urban fabric is adjusting to successive riverbanks and coastlines. The concept of hybrid urban delta is defined and applied to deltaic landscapes. This study promotes combined geoarchaeological, geohistorical, and geographical approaches to reconstruct temporal trajectories of river deltas, port-cities, and harbours.