Steam locomotives hauled wooden carriages through gas-lit tunnels between Paddington and Farringdon as the Metropolitan Railway carried its first fare-paying passengers. Nearly 40,000 people rode on opening day, proof of pent-up demand for relief from London's notoriously congested streets, and the model soon spread to cities worldwide.
London in the mid-19th century was choking on its own success: horse-drawn traffic clogged the streets, and the population had exploded past two million. Engineer John Fowler pioneered the "cut and cover" method, digging a trench along existing roads, laying track, and roofing it over, to build a railway beneath the chaos above.
The experience was smoky and sulfurous, since steam locomotives ran through tunnels with only partial ventilation, but Victorian Londoners embraced it anyway, packing the carriages to capacity. Some carriages were lit by gas lamps fed from rubber bags stored on the roof, an arrangement that today sounds alarmingly flammable.
The Metropolitan Railway's success proved that mass underground transit was commercially and technically viable, inspiring subway systems from Budapest to New York to Tokyo. Today's London Underground, still partly running on some of those original Victorian tunnels, carries over a billion passengers a year, a direct descendant of that smoky first journey in 1863.
Key people: John Fowler