Gibraltar’s historic half-oral, half-written bilingual streetname system is related to its eighteenth-century founding multilingual population. Using the geolinguistic concept of types of mobilities, a community of spatial practice is identified, which serviced forts in Gibraltar, Menorca, Ceuta and Melilla, predominantly hailing from Britain, Genoa, Menorca, Morocco and Portugal. We use the term ‘spatial practice’ in the sense that these speakers made recurrent journeys around Western Mediterranean forts over generations, establishing a conduit of language interchange. The linguistic feature studied here is surnames, which entered Gibraltar streetnames over an extended period of time, constituting an archaeological trace of a subset of British Gibraltar’s founding families. Gender is implicated in this account, as the Gibraltar Spanish streetnames were transmitted by Spanish women who married Gibraltarians, creating Gibraltarian hispanophone domestic environments. These are now in the process of being lost as the older generation has ceased speaking Gibraltar Spanish to children, a consequence of Franco’s closure 1969-1985 of the land-border. This loss of cultural heritage is significant as the concept of a historical Gibraltarian identity is challenged whenever politicians question Gibraltar’s sovereignty. Our analysis demonstrates that the continuity of a cohesive tricentenarian community is audible (if only partially visible) in its bilingual streetscape.