This historical account will try to re-evaluate the scraps of occupation evidence attributed to the Helvetii of the Swiss plateau recovered solely from both Roman and medieval urban settings, in the context of the conduct of XXth century research, from the first haphazard observations to the systematic rescue projects of recent decades. Particular attention will be focused on the key settlement of Yverdon-les-Bains (canton of Vaud), where relevant finds were first made in the 1940s. The slow progression of the recognition of the evolution of this Late La Tène agglomeration can be followed, primarily from the second century BC through its brief elevation to oppidum status in the following century. More recent discoveries in the medieval centres of Lausanne and Zurich will also be considered, taking into account evidence for continuity (at Zurich, as at Yverdon) or of discontinuity (the case at Lausanne) noted during the Roman and High Medieval periods. Also of significance is the weight of historical information and epigraphic evidence in the processes of the identification and interpretation of the significance of archaeological sites such as Eburodunum and Turicum which have been brought to light by more piecemeal and haphazard methods.