The World's Longest Tunnel, Step by Step
A giant drill makes drillholes to be filled with explosives at the construction site for the Gotthard Base Tunnel on April 19, 2007 near Sedrun, Switzerland. Deep beneath the Alps, the Swiss set out to build a high-speed rail link between Zurich and Milan. At 35 miles, te Gotthard Base Tunnel would be the world's longest tunnel.
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