|“||There was victory and defeat; and towers fell, fortresses were burned, and flames went up into the sky.||”|
–The Fellowship of the Ring, In the House of Tom Bombadil
They are made from Arnor bricks and its variants with iron bars in the windows. It will be hard to scale as it has no stairs or ladders.
At the very top, there is a chest with valuable loot, including precious metals (gold, iron, silver), weapons, remains of inhabitants (bones, skulls, etc.), and rare Arnor armour and equipment. As of public beta 25, this chest is a stone chest. Since the stairs are no longer intact, the best way to get to the loot is to pillar jump up the side, or if you're evil, ride a spider up it.