The work which bears the title of is usually attributed to the emperor M. Aurelius Antoninus. It is also ascribed in the MSS. severally to Julius Caesar, Antonius Augustus, Antonius Augustalis, and Antoninus Augustus. It is a very valuable itinerary of the whole Roman empire, in which both the principal and the cross-roads are described by a list of all the places and stations upon them, the distances from place to place being given in Roman miles.

We are informed by Aethicus, a Greek geographer whose Cosmographia was translated by St. Jerome, that in the consulship of Julius Caesar and M. Antonius (B. C. 44), a general survey of the empire was undertaken, at the command of Caesar and by a decree of the senate, by three persons, who severally completed their labours in 30, 24, and 19, B. C., and that Augustus sanctioned the results by a decree of the senate. The probable inference from this statement, compared with the MS. titles of the Itinerary, is, that that work embodied the results of the survey mentioned by Aethicus. In fact, the circumstance of the Itinerary and the of Aethicus being found in the same MS. has led some writers to suppose that it was Aethicus himself who reduced the survey into the form in which we have it. The time of Julius Caesar and Augustus, when the Roman empire had reached its extent, was that at which we should expect such a work to be undertaken; and no one was more likely to undertake it than the great reformer of the Roman calendar. The honour of the work, therefore, seems to belong to Julius Caesar, who began it; to M. Antonius, who, from his position in the state, must have shared in its commencement and prosecution ; and to Augustus, under whom it was completed. Nevertheless, it is highly probable that it received important additions and revision under one or both of the Antonines, who, in their labours to consolidate the empire, would not neglect such a work. The names included in it, moreover, prove that it was altered to suit the existing state of the empire down to the time of Diocletian (A. D. 285-305), after which we have no evidence of any alteration, for the passages in which the name "Constantinopolis" occurs are probably spurious.

Whoever may have been its author, we have abundant evidence that the work was an official one. In several passages the numbers are doubtful. The names are put down without any specific rule as to the case.