Monday, 14:45 
Greatest Train Journeys From Above
Switzerland's Glacier Express
Connecting iconic mountain resorts St Moritz and Zermatt, the Glacier Express is filmed from above, winding along alpine peaks, over treacherous gorges and through vertiginous mountain ranges. It's a constant struggle to keep on track as engineers battle deep snow drifts, harness the latest tech to protect the line from landslides and set explosives to guard against deadly avalanches.