Washington/Quebec City - A stretch of Alpine railways that connect Thusis in Switzerland via St Moritz to Tirano in Italy were added to the list of World Heritage sites by UNESCO.

The 128-kilometre rail designation includes the Albula line and the Bernina pass lines operated by Switzerland's Rhaetian Railway. The lines pass through Alpine mountain towns and landscape and through the language divides of German, Romansh and Italian cultures.

The train lines, opened in 1904, had major social and economic impact on the isolated life of the central Alps early in the 20th century, and represented engineering marvels for the time, the UNESCO committee noted late Monday about its decision.

The line passes through 55 tunnels and covered galleries and crosses 196 viaducts and bridges.

Earlier on Monday, Mantua and Sabbioneta, two historic cities in northern Italy's Po valley, were added to the World Heritage list. (dpa)