The paper presents on-going multidisciplinary geoarchaeological work and excavations by an international team of researchers from the universities of Gent (B), Cassino (I) and Évora (P), in and around the Roman urban site of Ammaia in the northern Alentejo region of Portugal. In this contribution we wish to characterise and visualise the site and surrounding study area, briefly discuss the aims and approaches of the chosen geoarchaeological strategy and fieldwork and report on some major preliminary observations and results, obtained during several field campaigns between 2001 and 2008. These results concern foremost three fields of archaeological questioning with specific relevance to the archaeological cityscape and general landscape background of the Roman town: the mapping and analysis of the ancient urban pattern and monuments (city wall, street grid,public buildings…), the provisioning of water for the Roman Imperial city and the important mining (gold, iron…) and quarrying activities (granite, rock crystal,…) connected with Roman occupation of this area.