This paper revisits the historical chronicles traditionally used to define the maximum damage area generated by the 1356 Basel (Switzerland) earthquake, one of the largest and most damaging intra-plate earthquake ever known in Europe. This work was prompted by a little known historical study detailing the castles in existence at the time of the earthquake and mentioning whether they suffered damage or not during the quake. This new data set suggests that a few damaged castles assumed to be situated in French Sundgau were probably ill located. Starting from the original historical chronicles, we propose new locations for these castles. Applying the hypothesis that chroniclers listed the damaged castles as if following an itinerary, we found localities where castle ruins are still in place today, and were bearing similar names to the inappropriately located castles. The new damage distribution of the 1356 Basel earthquake is now more compact and concentrated around Basel. To extend the value of this new interpretation, we modelled the fault and the earthquake parameters that generated the damage with BOXER, a macroseismic intensity inversion software. The modelled earthquake has a magnitude of 6.2 and was located on a modelled fault striking ENE–WSE. The distribution of the 650 years old seismic damages, however, only recounts the cumulated effects of two main shocks and about a dozen aftershocks. Therefore, substantial ambiguities remain on the field identification of the seismogenic fault.