Salisbury Cathedral is mentioned by author Ken Follett as one of two models for his best-selling historical fiction novel The Pillars of the Earth. In this image, the buttresses that bear the force of the outward thrust of the exterior walls that results from the weight of the vaulted roof can be clearly seen. Buttresses as an engineering and architectural technique came directly from the challenges attendant to building cathedrals, in which the design goal was a large, uninterrupted volume beneath a vaulted ceiling.