Size: 1 ss
Cost: 1,000 gp
Prerequisites: Two guards per shift
This room sits atop a gate or gatehouse, usually in an exterior wall. It features murder holes/arrow slits (included in the price) in the floor, through which the guards can attack those in the area below (little more than a hallway that usually includes a portcullis or sturdy door at each end).
The barbican requires two guards on duty at all times.