Since the beginning of the 20th century, the clearing of 37 acres (15 ha) of remains as well as observations made during town planning works have provided valuable information on the ancient Roman town of Vasio in Vaison-la-Romaine. At its height (end of the 1st and 2nd centuries AD), it extended over 148 to 185 acres (60 to 75 ha) on the right bank of the Ouvèze river, already dammed in its urban crossing and lined with buildings. The containment system was based on large stone slabs and a scattering of oak stakes and spacers, whose year of felling (81 AD) could be precisely established. Most of Vasio, however, remains buried under the current town, and only certain residential, commercial or artisanal districts and some public monuments have been excavated.