The two single-track tubes of this railway tunnel were completed in 1905 and 1921, respectively. With a length of almost 20 km, the Simplon Tunnel remained the longest tunnel in the World until far into the second half of the 20th Century. It connects Brig (NW portal seen in this photo) with Iselle in the Val d'Ossola (Italy) and can be considered a base tunnel at least on the Swiss side.