Book of Fortresses

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.

Contemporary research shows early spring 1509 as the start date of the work trip in Castro Marim, until their completion, seven months later, in September in Caminha.

Some notable drawings include humans and donkeys in Castelo Branco; pastors in Monsanto and Almeida; women who were fetching water in Ouguela and Montalban; or the hanged in Castle of Serpa and Elvas, an act which, paradoxically, give life to the images.

In addition to the written comments, the drawings themselves reveal the great power of the author's observation and attention to the essential part of the dept of the manuscript: the fortresses, that is, the walls, albarrã towers and keep, barbicans, breastplates, turrets, and battlements.

The same is repeated in relation to plants, where it indicates the size, type and state of the defenses, height and thickness of the walls, distance between towers and turrets, purpose of magazines, access and others.