Perched on the edge of a basalt cliff, a town peers at the river running below. Today's image takes us to Castellfollit de la Roca in the Catalonia region of northeastern Spain. This town isn't for the faint-hearted: there's a 49-metre drop down to the Toronell and Fluvia Rivers, which converge at the base of the cliff. Many of the buildings, which are made of the same basalt that the town stands on, seem to teeter on the edge of the precipice. Pictured at the end of the crag is the 13th-century church of Sant Salvador.

Castellfollit de la Roca is inside the Zona Volcànica de la Garrotxa Natural Park, which has around 40 extinct volcanoes. Although there haven't been any eruptions for around 11,000 years, the area is still considered seismically active. In 1428, a major earthquake struck the area, which was felt in Barcelona more than 80 kilometres away. The last seismic activity was registered in 1901 and 1902, when there were two minor earthquakes. These days, the park is a popular spot among hikers, who head to Garrotxa to enjoy the region's spectacular volcanic landscapes.