In the last decades the evaluation of the seismic risk are of rising concern, considered essential in the activity and
definition of strategy planning and urban management. The evaluation of the seismic vulnerability of the existent building stock
in the perspective of the seismic risk mitigation should not be placed only in relation to the isolated buildings of relevant
historical and cultural importance, but also, in relation to the agglomerate of buildings in urban centres. The chronological
construction process frequently results in characteristic heterogeneity of masonry and wall connection quality. In addition,
buildings do not constitute independent units given that they share the mid-walls with adjacent buildings and the façade walls are
aligned. This way, as post-seismic observations proved, buildings do not have an independent structural behaviour, but they
interact amongst themselves, mainly for horizontal actions and so the structural performance should be studied at the level of the
aggregate and not only for each isolated building. In most cases, for masonry structures there is no need for sophisticated
dynamic analyses for seismic resistance verification or vulnerability assessment. This is even more relevant when an assessment
at the level of a city centre is pursued. In this work, the results of evaluation of the vulnerability will be presented in accordance
to three proposed methodologies based on a vulnerability index that consequently allows the evaluation of damage and creation
of loss scenarios (economical and human) not only at the level of the building and its façade walls but also at the level of the
aggregates. It will be discussed and evaluated the application of the referred methodologies and its integration in an SIG
platform