This volume presents archaeological and geomorphological evidence from the important, and well-preserved ancient harbour of Frejus, the result of a multidisciplinary program of research initiated in 1986. This program is based on the analysis of numerous sites and includes information drawn from soundings, excavations, topographical drawings and the study of artificial structures inside and around the harbour basin, as well as the palaeogeographical study of its environment. The findings shed new light on the topography and development of the harbour, from Iron Age lagoon to the development of the Roman harbour and its structures.