From 1853 a series of imperial decrees under Napoleon III gave Prefect Georges-Eugène Haussmann sweeping powers to expropriate property, demolish buildings and drive wide new boulevards through the dense medieval core of Paris. The legal framework, building on earlier expropriation law, allowed the state to assemble land along projected routes and finance the works partly through the rising value of cleared sites. Tens of thousands of buildings were demolished and rebuilt over the following two decades. The decrees enabled coordinated action at a scale private initiative could not achieve.
They provided the legal machinery that made large-scale, state-directed urban surgery possible, transforming Paris into a model of the modern boulevard city. The Haussmann model of expropriation-driven renewal became a template, and a cautionary reference, for ambitious urban transformation worldwide.