Agger (ancient Rome)

The word is sometimes applied to fortifications, such as the Agger Servianus, a part of the Servian Wall of Rome, which protected the city on its most vulnerable side, the Campus Esquilinus.

In modern usage however, particularly in British archaeology, it is most commonly used to describe the ridge or embankment on which Roman roads were built.

Finally, the agger was metalled with small stones in a matrix of smaller materials such as gravel and earth, and cambered to ensure good drainage off the road surface.

The aggers of a few important Roman roads in Britain, and in Europe, survive as high linear mounds and until relatively recently many scholars believed that they were built that way.

For example, Ermine Street north of Lincoln, which survives in places up to 1.5m high and in excess of 15m wide, was described by Margary as being 'one of the most magnificent in Britain, rivalled only by Ackling Dyke'.