Despite the absence of any institutional framework, or even systematically and coherently published and publicised opinion, the idea of putting forward the Pombaline "Baixan, or old downtown district of Lisbon, for World Heritage listing has been evaluated summarily by several political and cultural institutions, and the possibility of preparing and organising such an application has been discussed, albeit without a formal presentation or accompanying documentation, by successive executive committees of the Lisbon City Council. The fundamental aspects of Lisbon's urban reform are well known, nowadays, through the abundant, recent bibliography, based upon the classic study by Jose Augusto Franp (1965). As a result of the destruction of the greater part of the city, including the symbolic centres of power, by the 1755 earthquake, - the most violent registered in history, and a catastrophe which, at the time, became the subject of literary and philosophical works - a complex reconstruction scheme was imposed by the commanding figure of the Marqugs de Pombal. Confronted by the different alternatives, it was decided to rebuild part of the city from scratch, on the basis of a strict legislative programme and a series of practical principles and methods inspired by Portuguese military engineering experience and urban experiments in the colonial territories. Although the logic behind the physical limits of the Pombaline "Baixa" is rather unclear-and somewhat fluid in certain zones which border on more ancient urban sectors-it is possible to identify an area of 235,620 square metres, covering 62 blocks and 430 building lots, not including the extension of the Pombaline city to other growth nuclei. (Santos, 2000). In any event, in its commonly accepted dimension, the property under analysis is one of the most singular heritage clusters to have survived in Portugal, although in the last century, careless and erratic management may have jeopardised important features of authenticity and singularity, perhaps irreversibly. The exceptional character of the whole process of planning and construction is apparent, first and foremost, in the modernity of the conceptual presuppositions which were laid down, which make the Pombaline reconstruction of Lisbon one of the first, contemporary, large-scale, town-planning schemes: a. Exact definition of reconstruction limits; b. Exhaustive planning of the process; c. Topographical survey and mapping d. Creation of an inspection system e. Functional presuppositions for urban design - regularity of design, control f volumes, even if altered. f. Programmed architecture g. Hierarchisation and articulation of reconstruction nuclei, according to the new Power structure h. Functional infrastructures (sanitation and sewerage) i. Integral planning of fapdes j. Possible construction with prefabricated units k. Studies and implementation of anti-seismic and anti-fire building systems I. Subordination of the single building to the preestablished grid m. Articulation with the previous urban pattern, adapted to the topography n. Respect for the place and the landscape o. Definition of transition zones for areas within the old urban pattern. The maintenance of monumental spaces, subtly integrated within the urban grid- Pram do Comercio and Rossio - the punctuation and interruption of the dominant architectural features by means of the reconstruction of stereotyped but confidently designed religious buildings, the exploitation of the river backdrop and the morphology of the terrain, all contribute towards the creation of an urban landscape of rare beauty and consistently unified design, the most monumental testament ever built in the name of the political and philosophical principles of the Aufklarung. Whilst similar to certain other examples (Edinburgh, Turin and London, amongst others,) it is clearly superior in its radical modernity, its functionality, and the architectural quality of its programme. The Plan of Sir Christopher Wren and others for London, after 1666, does not implement overall principles.