This book presents the results of the colloquium "Ricerche Archeologiche alla Foce del Tevere" which was held on 18-20th December 2018 in Rome and Ostia. It provided young researchers with the opportunity to present their own research on ancient Ostia and the surrounding territory to the scientific community. The collection of papers presented here shows new evidence, new analysis tools, new approaches and new questions. The contributors have used the latest technologies and scrutinized archival records which are a valuable source of information that remain often unpublished. The scale and range of the analyses are impressive, from the molecular identification of pigments, to the remote-sensing study of broad swathes of the Ostian landscape. The chronological spread is also notable, from the late 6th-5th centuries BCE to the 5th-early 6th centuries CE. These proceedings are divided into four parts showing broad-ranging subjects: the first part tackles Ostian urbanism and territory; the second building activities from designing to decorating; the third religion; and the fourth archaeological finds.