Castrum (also Roman castrum; Latin Castrum, plural castra, diminutive castellum) is a common type of Roman military settlement, a military camp during antiquity.
Thanks to castrums the Roman Empire was able to establish itself not only in the coastal Mediterranean, but also to conquer a number of internal regions of Europe (Gaul, Dacia, Meuse, Iberia, Pannonia).
Many modern cities of Southern and Western Europe sprang up on the site of the former castrums.
