Drawbridge

Create 8 Goods, 2 Influence, 5 Labor (320 gp); Time 6 days
Size 4—8 squares
This retractable bridge spans a pit, moat, or similar danger, allowing you to control access to an area. You can raise or lower the bridge by spending a full-round action to operate the mechanisms constructed on either side of the span. When raised, the bridge creates a wooden barrier (hardness 5, 40 hit points). If the Drawbridge is destroyed, it can be rebuilt in the same place for half the initial construction price.