De Re Aedificatoria, completed by Leon Battista Alberti around 1452 and printed in 1485, was the first major architectural treatise of the Renaissance, modelled on the Roman writer Vitruvius. In ten books it set out principles of building and town design grounded in proportion, decorum and harmony, treating the city as an ordered composition with a rational hierarchy of streets, squares and public buildings. Alberti argued that beauty arose from the reasoned relation of parts to the whole and that the city should be planned for dignity, health and defence. Written in Latin for an educated patron class, it framed architecture as a humanist, intellectual discipline.
It launched Renaissance ideal-city theory and the conception of the city as a designed work of art governed by reason and proportion. Its ideas informed centuries of European urban design, from piazzas and axial streets to the planned ideal towns of the era.