In this article, I interrogate the textual form and discuss the central importance and meaning of the architectural design of William Beckford's Vathek, and I trace the formal features of architecture that inform the novel. Rather than contextualizing the novel in terms of biography, reading it as inscribed with Beckford's personality, or offering an exploration of the characters' psychological makeup, I focus on Beckford's narrative and his ability to construct a polygeneric tale of Gothic didacticism. Despite writing Vathek in 1782, at the age of twenty-one, and retailing a myth of its spontaneous composition, Beckford crafted a text that reveals a highly finished architectural design and skilful inversion of the conventions of romance.