Tower Battlements is part of the City Builder System. Tower Battlements is made of "Dwarvenite." Tower Battlements was initially available as Add-On item during the City Builder System Kickstarter. The item comes in both painted and unpainted versions.
Tower Battlements comes with these 14 pieces:
(6) Corner, Crenellated
(2) Corner, Crenellated, Trap Door
(2) Pillar, Dwarven
(4) Straight Crenellations