From Pathfinder #146: Cult of Cinders, which isn't enabled.

Rebuild Battlements

ACTION

Requirements Crafting (expert), Specialty Crafting (stonemasonry), or hired stonemason; organized workers

You rebuild and restore the collapsed battlements along the northern section of the central tower. This task takes 28 days of work and a DC 20 Crafting check.

Pathfinder #146: Cult of CindersOGL