in the Ancient Military Art, a work of fortification, used both for the defence and the attack of towns, camps, &c.; in which sense it is the same with what was otherwise called vallum, and in later times aggestum; and, among the moderns, lines, sometimes cavaliers, terrasses, &c. The agger was usually a bank or elevation of earth or other matter, bound and supported with timber; having sometimes turrets on the top, wherein the workmen, engineers, and soldiery were placed. It was also accompanied with a ditch, which served as its chief defence.

The height of the agger was frequently equal to that of the wall of the place. Caesar tells us of one he made which was 30 feet high and 330 feet broad. Besides the use of aggors before towns, the generals used to fortify their camps with such works.

in Ancient Writers, likewise denotes the middle part of a military road, raised into a ridge, with a gentle slope on either side, to make a drain for the water, and keep the way dry.—The term is also used for the whole road or military way. Where highways were to be made in low grounds, as between two hills, the Romans used to raise them above the adjacent land, so as to make them on a level with the hills. These banks they called aggores. Bergier mentions several in Gallia Belgica, which were thus raised, ten, fifteen, or twenty feet above ground.