Numerous renowned antiquaries and architects in Georgian Britain were enthralled by a strange craze: they declared the ark of Noah to be the origin and divine model for architecture worldwide. This article analyses the fashion for ‘arkaiology’ (as the poet Robert Southey mockingly called it) by focusing on one of its most spectacular exponents, the architect Joseph Michael Gandy (1771–1843). Taking Gandy’s theories as the starting point to reconstruct a broader debate on climatological thinking about art and architecture, the article shows that the fascination with the deluge is best understood as a reaction against the climatic theory of the origins of architecture associated with Johann Joachim Winckelmann and the implicit cultural relativism that it entailed. The case of Gandy also sheds fresh light on the search for origins in late (Romantic) classicism. Instead of submitting to a climatically determined vernacular tradition, Gandy’s arkaiology allowed him to theorise the distant past as a space for speculative artistic reconstruction of the principles of architecture.