An old Roman wall?

Ok that's enough ranting about religion and power and wealth. Here's an old Roman wall. At least that's what I assume. There's no signage but the bricks are unmistakable and what else in this state would you take such care to preserve. We see it as we leave the cathedral looking for a nearby park to to rest our feet. We're already tired. It's the middle of our holiday and the fatigue is setting in.