Castellfollit de la Roca is a municipality in the comarca of Garrotxa, in the Province of Girona, Catalonia, Spain. The urban area is bordered by the confluence of the Fluvià and Toronell rivers, between which the town’s basalt cliff rises.
The basalt cliff
The basalt crag where the town is situated is over 50 meters (160 feet) high and almost a kilometer long. It was formed by the overlaying of two lava flows.
Hopefully there is no earthquake faultline in the immediate area.