The stronghold of Iudeu, which Bede called urbs Giudi, appears to have been a royal centre held by the seventh-century kings of the Bernician English, and sufficiently prominent to lend its name to the Firth of Forth in the British and Gaelic languages. The name appears not to have survived in any modern place -name, leaving us reliant on Bede's vague description of the site in Historia Ecclesiastica Gentis Anglorum, as well as a few other scraps of circumstantial evidence, in seeking to locate it. The situation naturally encouraged debate among scholars until, in 1959, identification with Stirling was proposed. This article reviews both that hypothesis and the primary evidence relating to Iudeu, and argues that the Stirling identification is far from satisfactory. Two new alternatives – and a third one, discarded in 1947 – are put forward as sites most in keeping with the crucial evidence provided by Bede, but no firm decision between them seems possible in our present state of knowledge.