Rimini is located at the southernmost end of the Po Plain, in Emilia-Romagna region. The geomorphology of the site mainly depends on the actions of the Marecchia River, coupled with marine processes in Holocene times. By creating a geomorphological map of the area, we highlight the factors that influenced the historical evolution of the town, relating them to anthropic features, with acmes in natural changes probably matching periods of climate deterioration. Many clues suggest that the Marecchia river pattern changed frequently and drastically during the climate deterioration of the Early Middle Ages, when the river’s name changed from Ariminus to Maricula (‘little sea’). The river frequently aggraded and overflowed during the climate deterioration of the Little Ice Age and until the early twentieth century. The urban geomorphological map, implemented according to the official ISPRA cartography criteria, has enabled us to highlight valuable elements for reconstructing the evolution of the town, that are now almost completely hidden by urbanisation.