Essai sur l'architecture militaire au Môyen âge
Viollet-le-Duc's 1854 Essai sur l'architecture militaire au Moyen Âge, published in Paris by the Libraire d'architecture de Bance, is a treatise on medieval fortification written for architects and students of building. The pictures are plain line drawings of castle and town plans, with a masonry vault detail, that show how walls, towers and gates were laid out, useful to a designer wanting schematic floor plans and defensive outlines.
