A ‘site’ is one of the key concepts in archaeology, and is not specific to central Italian archaeology. Archaeologists have tried to define what constitutes a site and how it can be measured. One definition of a site is ‘as places where significant traces of human activity are identified’ (Renfrew & Bahn 1994: 42). Essentially, a ‘site’ has to be distinguished from a ‘non-site’ and the boundary between the two has to be drawn (Carman 1999). These definitions made in the field are archaeological decisions, not observations (Dunnell and Dancey 1983). Our practice is a pragmatic act of constructing boundaries on the basis of the density of finds and/or features. The definition of a specific site is subject to evaluation of the archaeological criteria used to define it. However, it is clear that the concepts behind those criteria have changed over time. In central Italian archaeology, the scholars have moved from the topographical archaeology of the 19th century to the GIS-assisted landscape studies of the 21st century and their definitions have evolved similarly. Central Italy is relevant as an example since Italian studies have contributed fundamentally to the developments in field archaeology.