5. Arlberg, Austria
Western Austria hosts one of the longest tunnels, Arlberg with 8.7 miles, in the world. The tunnel is situated to the North of Rhaetian Alps in Austria. The divide between Rhine and Danube River is formed by this mountain pass. The region is famous for winter sports. Hannes Schneider perfected a skiing technique called Arlberg Technique in this region only. There is one more rail tunnel which was constructed way back in 1880-1884 when nobody could dare to even think of constructing such a long tunnel.