This paper presents an overview on the geology of the city of Roma and illustrates how the city and its evolution has been significantly affected by the active interaction with the geological environment both in terms of resources and hazards. Roma, with its 3000 years of history, represents a unique case, a laboratory for urban geology. The city is still currently exposed to several hazards and the knowledge of geology is mandatory to mitigate and prevent the effects of future events such as earthquakes, volcanic gas emission, floods and landslides. At the same time, the correct management of the water and land resources need a careful planning in consideration of the very high level of anthropic pressure on the local environment. The study of the geology of Roma and its intimate relationships with the urban development of the city have been strongly influenced by the ideas of Renato Funiciello, recently passed away, to whom this paper is dedicated.