Book of Fortresses

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The Book of Fortresses (Portuguese: Livro das Fortalezas) is a sixteenth-century manuscript written in 1509–1510 by the Royal Clerk Duarte de Armas at the behest King Manuel I of Portugal. The work contains drawings of all the 56 Portuguese border castles, all of which have been personally visited by the author. The book is considered to be a valuable source for the study of cartography and military architecture of the kingdom of Portugal.^[1]