Today, lovingly restored, almost 100-year-old carriages take tourists along the 120-kilometre (80-mile) line from Rome to the Roccaraso ski resort to the east, passing over countless precarious viaducts. The Sulmona-Roccaraso section, reaching an altitude of 1,269 metres (4,163 feet) at its highest point, was opened in 1897 and is a feat of engineering, winding its way up the steep, rocky mountainside in a series of long, elegant loops.

The self-described "low-speed travelling museum", widely known as the Italian Trans-Siberian, passes through myriad tunnels and narrow cuttings, past frozen lakes and snowy forests.  Even the occasional wolf can be seen along the way. "It's really an amazing experience, going back in time, with these slow-moving trains, rather than really fast ones where you can't see anything outside," said Neapolitan tourist Elisabetta, travelling with her partner and 10-year-old son Giosue.