London has always had an underground life, from its many crypts and tunnels to its numerous underground rivers, since the Romans, and this can be seen in the remains of a military fort beneath the Museum of London. To go underground in an attempt to ease the disastrous effects of the post-industrial revolution on London, when as a city its population more than doubled from under 1 to over 2.5 million in 50 years between 1800 and 1850, seemed an obvious solution.
Historically, the person credited with the first idea for underground transportation in London was one Charles Pearson who, in 1845, published a pamphlet that suggested using the Fleet River, which runs underground from Hampstead via Kentish Town and Farringdon to join the Thames at Blackfriar's Bridge. In fact, Farringdon Road is the Fleet valley under which the river runs, and Holborn Viaduct was built to cross it. Pearson's idea was that passengers would be transported by trains in some sort of fantastical glass tunnel.
Engineering was a big feature of progress in Victorian England. Following the "Big Stink" of 1858, civil engineer Joseph Bazalgette designed an underground sewage system of 450 miles of main sewers, and 13,000 miles of interconnecting local sewers, which remains the mainstay of our system today. Bazalgette, by then knighted, went on to work on the Blackwell tunnel, now borrowing under the Thames itself.
The scene was set. Finally, the parliamentary bill received Royal Assent, but funding was still to be found. The work was to be executed by one John Fowler, from Sheffield who had cut his teeth on the railways of Yorkshire and Lincolnshire, and finally in 1860 work began on the world's first underground railway system, the Metropolitan line.
Using a system of "cut and cover" roads were literally dug up, railway tunnels cut out, and then covered up and the roads replaced. Hugely labour intensive and disruptive, it took three years to complete the first track which ran from Bishop's Road, Paddington to Farringdon Road, finally opening to the public on Saturday January 10th 1863.