Turris Portus Ubiorum
About
The oldest known stone structure in Cologne: a tuff-stone tower roughly 9 meters square and originally about 12 meters tall, marking the entrance to the Rhine harbor of the pre-Roman Ubian settlement. Tree-ring dating puts its oak-pile foundations in the winter of 4–5 CE. The later city wall, built around 90 CE, cut into the tower, so only a reduced stump of the original structure was still standing by 117.
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
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 →