City Wall of the Colonia
About
A stone fortification circuit roughly 4 kilometers around, with at least nine gates and nineteen round towers, enclosed the colonia Rome founded in 50 CE, and builders raised it around 89-91 CE, late in the 1st century. The foundations ran 3 meters wide and 3.2 meters deep, fronted by a defensive ditch up to 12 meters across, and rested on wooden shuttering that anaerobic, waterlogged soil preserved intact for two thousand years. Dendrochronology on that timber traced the felled conifers back to the Black Forest, floated down the Rhine and sawn to size on site in Cologne. By 117 CE the wall defined the full built-up extent of the city, marking its northwest corner with what is still known today as the Roman Tower.
What happened here
A town wall is a claim as much as a defence. It is faced in stone, cored with rubble and concrete, and pierced by gates that are more decorated than the rest of it put together. Towers project so that anyone at the base can be shot from the side. In most of the empire in this century the walls are old, unmanned, and half built over — shops lean against them and houses are cut into them — because the frontier is a long way off and the danger is not here. On the frontier itself a wall is something else entirely: a continuous barrier with ditches, gates at intervals, patrol tracks and manned turrets, built to control movement rather than to stop an army.
Sources
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Roman Maps shows the empire frozen at 11 August 117 CE, the day Trajan died — its moment of greatest territorial extent. Explore the full map →