A fault in the Apennine Mountains wreaked damage on structures including the Colosseum. The geological fault responsible for a series of Italian earthquakes in 2016 might also have caused a quake mentioned in ancient accounts of fifth-century Rome. Until 2016, scientists had considered the 30-kilometre-long Mount Vettore fault in the central Apennine Mountains to be dormant. But between August and October that year, it generated three big earthquakes; the first killed nearly 300 people. To explore the fault’s history, a team led by Paolo Galli at the Department of Civil Protection in Rome dug trenches across it to look for...