From numismatic findings and recent excavations in the Old City of Jerusalem it emerges that the preparatory work on Aelia Capitolina started at the very beginning of Hadrian’ reign, most probably in the 120s, more than a decade before the Bar Kokhba war. The question then arises as how it happened that Eusebius mentions the founding of this colony as a consequence of the war. The answer lies both in the source he depends upon, possibly Ariston of Pella, and also in Eusebius’ own conception of Jewish history.