The work of the map-maker and historian Humphrey Llwyd (1527–68) were a crucial contribution to a new vision of Britain in the early modern period. It lies close to the roots of the emerging ideology of British Empire, and Llwyd’s influence is to be found in the works of major English poets such as Edmund Spenser and Michael Drayton. His history of medieval Wales, Cronica Walliae, shaped Welsh historical traditions for centuries to come. Llwyd is also the earliest extant source for the legend of Prince Madoc, whose twelfth-century voyage to America shaped British fantasies of the New World from the reign of Elizabeth to the nineteenth century. This is the first book-length study of Llwyd’s works, influence and intellectual milieu, and contributions from scholars in the fields of history, geography and literary studies cover the range of Llwyd’s achievement as a cartographer, historian and chorographer of Wales and Britain.