A Foundation looks like a mountain’s root: a pillar of grey and black stone as wide as a castle keep and many times as tall, rising from nothing beneath and ending in the underside of a floating island. Veins of gold and copper glow in it and pulse slowly, like a heartbeat. Here and there a shape shows in the stone, a vast shoulder or the line of a closed eye, but it never moves. A deep hum comes from it that a visitor feels in the bones, and stone pressed against it is warm.

They stand beneath the floating islands of the Iron Backbone, each holding up its own, and at the points where the plane’s geometry must be held.

They hold. A Foundation does nothing else, and seems aware of nothing but what it holds. Whether they think is not known; the Stonewrights speak of them with respect, as one speaks of an elder.

They are what makes the Backbone stand. Their danger is only what would follow if one failed.

Travellers say that on the Backbone even the mountains have a spine, and the Foundations are what they mean. Scholars on Caeldon sometimes speak of foundation-stones of the world, and whether they mean the Foundations or only use the figure is not always clear.