By Makaristos – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=14666845

The Ostia Synagogue is an ancient Jewish synagogue and archaeological site located in ancient Ostia, the seaport of Imperial Rome, in present-day Lazio, Italy. It is one of the oldest synagogues in the world, the oldest in Europe, and the earliest known mainstream Jewish synagogue discovered outside the Land of Israel. The building dates to the reign of Claudius (41–54 CE) and remained in use as a synagogue into the 5th century CE.