The seismic vulnerability assessment of buildings in historic city centres is the first step to mitigate the possible damage, to prevent heritage losses and to preserve their historical identity. In this paper the analysis is focused on the residential buildings of "Ground zero Area" in El Cabanyal. This unique quarter of Valencia, once a fishermen's settlement, has a strong village-like identity and heritage value. Swallowed up by an expanding city centre and threatened by a poor redevelopment plan, which caused its degradation, its rehabilitation is nowadays the object of a new protection plan.The seismic vulnerability of the residential buildings has been assessed using the Vulnerability Index Method, obtaining a global damage index, and the equivalent built area expected to be destroyed. Results, implemented in a GIS environment, revealed that, due to the high vulnerability, many of the analysed listed buildings will be significantly damaged. A new detailed analysis is recommended, to define intervention and retrofitting criteria to improve their seismic response, preserving the architectural heritage and defending the unique identity of El Cabanyal.