CASTLE, in ancient writers, denotes a town or village surrounded with a ditch and wall, furnished with towers at intervals, and guarded by a body of troops. The word is originally Latin, castellum, a diminutive from castrum. Castellum seems originally to have signified a smaller fort for a little garrison; though Suetonius uses the word where the fortification was large enough to contain a cohort. The castella, according to Vegetius, were often like towns, built on the borders of the empire, where there were constant guards and defences against the enemy. Horsley considers them as much the same with what were otherwise denominated stations.