One of my first memories of the cinema is seeing a newsreel of lava pouring down the flanks of Vesuvius in 1944. This wasn’t its first eruption since the famous one of AD 79 that buried the cities of Pompeii and Herculaneum – there had been several others, such as in 472 and 1631 – but it was the first to be caught on film. The 1631 eruption killed some 3,000 people, mostly scattered around the Bay of Naples, but though ash fell on the city itself, it was saved by the intervention of St Januarius (San Gennaro), whose relics were brought out to halt the eruption. When the volcano next erupts, as some day it will, pictures of the event will doubtless be transmitted all over the world in what we now call real time. Meanwhile the Italian government has elaborate plans for wholesale evacuation of the surrounding towns (18 of them) and villages; ‘within 72 hours’ of receiving the first warnings, ‘600,000 residents of the Red Zone will be removed according to the specifications contained in the individual emergency plans for each community’. A formidable undertaking indeed; but then Vesuvius is itself formidable.

Ingrid Rowland, a professor at the University of Notre Dame School of Architecture in Rome, has been fascinated by Vesuvius and Pompeii since her first visit as an eight-year-old in 1962. Much has changed since then. Visitors see less of what has been excavated and restored than they used to,