The 32-mile Centovalli Line opened in 1923 to connect Domodossola, in Italy’s Piedmont region, and Locarno, in the Swiss Ticino.
The two-hour journey forms part of the route between Lake Maggiore, the French part of Switzerland, and the Swiss capital Bern as well as being the most direct connection between the Gotthard and Simplon passe.
Departing from an underground station in Locarno, the train travels through a valley which was carved by the Melezza river which has allegedly 100 adjoining valleys.
It passes 83 bridges and 31 tunnels, through the high point of Santa Maria Maggiore over the Italian border and along the Valle Vigezzo to Domodossola before descending into Domodossola.
The journey takes passengers past breathtaking gorges with crashing waterfalls, over spectacular bridges and passing through delightful villages.
Vineyards also line the route, which vary in style from the manicured hedges of Switzerland to the “ramshackle” family vineyards over the border in Italy.
The train can be taken from Locarno as a return day trip or as part of the Lake Maggiore Express day trip. It can also be used as a connection to Ascona with Montreux on Lake Geneva, Spiez and Thun in the Bernese Oberland, or the Graubünden mountain resorts.
Passengers are recommended to see the route in autumn, when the journey is lined with hundreds of deciduous trees, mainly sweet chestnuts turning orange and yellow.
It has been called “the best-value train ride in Europe” by the Telegraph with a return ticket costing about £30.
The Centovalli Line operates hourly services every day, throughout the year, with tickets available online from operator Vigezzina Centovalli.