The Castra Peregrina ("camp of the strangers") was a castrum (a military barracks) in Rome situated on the Caelian Hill.

Within the castra was a shrine (templum) of Jupiter Redux erected in honour of Severus and Mammaea by a centurio frumentarius.

It has been claimed by some authors, as the name suggests, that the barracks housed a garrison of peregrini, non-citizens and free subjects of the empire.

[5] Others, however, dispute this claim and have proposed that the barracks housed Roman citizens; if so, the name would not imply the lack of citizenship but rather refer to the fact that they were detached away from the legions for special services in Rome and elsewhere.

[6][7] They consisted of a majority of frumentarii[3] and inscriptions suggest that the Castra Peregrina acted as a central base for the distribution of these men throughout the unarmed provinces (inermes).