The Greatest Engineering Tunnels

This episode explores some of the world’s most impressive tunnels, including the Channel Tunnel beneath the English Channel, Switzerland’s Gotthard Base Tunnel, Japan’s Seikan Tunnel, and Norway’s Lærdal Tunnel. It examines how engineers overcame mountains, seabeds, unstable rock, water pressure, heat, and the complex infrastructure beneath modern cities. The episode also highlights urban subway systems, flood-control tunnels, advanced tunnel-boring machines, ventilation, emergency design, and the continuous maintenance required to keep these hidden structures operating safely. Ultimately, it shows that the greatest tunnels are not only feats of construction, but powerful symbols of humanity’s ability to overcome geography, connect distant regions, and build essential systems beneath the surface.