ou can build a pretty impressive defense with walls and towers. Unfortunately, from the military viewpoint anyway, Roman citizens and traders expect freedom in their comings and goings. That means that you have to provide openings in your defenses.

Now, these doors can be as simple as leaving a gap in the wall. Of course, when invaders see these openings, they will probably concentrate their attacks there. More commonly, governors build gatehouses at all of the city's entry and exit points.

Gatehouses are strong, protected by several sets of thick doors and walls, and are unlikely to be the subject of direct attacks themselves. Gatehouses confer one very useful benefit unrelated to their defensive role: Citizens don't like to venture outside the city itself unless they have to, so most stop and turn around when they reach a gatehouse. The only people who will venture into the wilds of your outer province are merchants, migrants, and friendly soldiers following orders.