The historical core of Paris is the most complex zone of the metropolitan area. Despite its continuity as the urban core since roman times, the substantial transformation during the XIXth century under Baron Haussmann and the subsequent works during the XXth century make it in many places a somehow recent urban tissue.
Under the reign of Napoleon III and for a not that long period (1853-1870), Haussmann directed a radical urban transformation. As well as Cerdá in Barcelona or the English reformers, he associated the old urban tissues from the middle ages to epidemics and social problems, and thought that transforming these areas was an urgent need.
His approach to the problem is similar to what can be seen today in many cities: a combination of a search for administrative efficiency that sometimes forgets any other goal, and a new paradigm. If today the paradigm is the idea of sustainable development, Haussman is the first example of what late will gain traction to reach its zenith around the first world war under the name of hygienism.
Fueled by new management techniques (which make him suspect of financial scandals), Haussman is not limited to the urban extension problem as Cerdá in Barcelona (whose ideas about refurbishment of the existing city never fully gain traction), as he also defines, with a central role in his urban model, a transformation of the central core by opening many boulevards that ensure a consequent streets grid. The sanitation and sewage system is an innovation in its days, due to its design and ambition, and the Seine shores receive embankments.
The romantic image of the XIXth century Paris that is transmitted by tourist guides is an abrupt change for the people that live these transformations. Elements that today have been integrated to the urban landscape and can be seen as unmistakably Parisian by tourists are in the beginning just mass- produced urban furniture fixtures that are placed in an uniform way on the public space.
Paris today is still marked by the Sebastopol and Saint Michel Boulevards, what was the large market of Les Halles (substituted by a large retailing mall in the 1970s and a large transit exchange, and nowadays again subject to substantial construction works for a new radical transformation) and the new embankments, plus the building of a large number of monumental scale buildings that are designed to highlight the axis of the new boulevards.
The difference between this experience and that of other cities is the high technical and aesthetical quality of the designs of these elements, as well as the inner coherence of the urban project, that would not be completed until after the fall of the second empire. The lack of a geometric basic system allowing for an extension ad infinitum of that new urban tissue, as Cerda’s grid, is not an obstacle to the continuity of the tissue, as that role is played by the Thiers Wall. While Barcelona and Madrid tear down their walls in 1860, in 1844 Paris opens a new external wall, in that moment far away from the urban area, but anyway a rigidity condition. These walls are demolished between 1919 and 1929, and later their vacant site becomes the location of the peripherique beltway, but to this day the 1844 wall marks a discontinuity in the urban fabric and is the administrative limit of Paris.