The Roman architectural terracotta study at Château-Thierry allowed the setting up of a methodology for the analysis of this material for the differents contexts encountered. The same elements are systematically examined in order to study the evolution of this material on the vicus and in its immediate vicinity. The model used is presented as well as the first possibilities obtained for the tiles unearthed in the end of the 2th and the 3th centuries contexts. The purpose of this presentation is to highlight a new point of view on architectural terracotta, often not studied, and to show the potential it offers in the understanding of Antique sites for the Château-Thierry region.