Simplon Tunnel Breakthrough

On June 21, 1904, workers achieved the breakthrough in the Simplon Tunnel between Switzerland and Italy, at 19.8 km the world's longest rail tunnel until 1979. Constructed by the Jura-Simplon Railway with innovative ventilation and electric lighting systems to combat heat and dust, it used steam-powered drills initially before electrification. Key engineers included Alfred Brandt. The tunnel dramatically shortened the Paris-Milan route by hours, enhancing European connectivity and trade while demonstrating advanced tunneling techniques that influenced later Alpine projects like the Gotthard Base Tunnel.