Marc Isambard Brunel's Thames Tunnel, the first…

Marc Isambard Brunel's Thames Tunnel, the first tunnel under the River Thames and the world's first bored underwater tunnel, is opened in London on March 25, 1843.

Under construction since 1825, using Marc Isambard Brunel's and Thomas Cochrane's newly invented tunnelling shield technology, by Brunel and his son Isambard Kingdom Brunel, the tunnel was originally designed for horse-drawn carriages, but will never be used for that purpose.

Although it was a triumph of civil engineering, the Thames Tunnel is not a financial success.

It had cost £454,000 to dig and another £180,000 to fit out—far exceeding its initial cost estimates.

Proposals to extend the entrance to accommodate wheeled vehicles had failed owing to cost, and it is used only by pedestrians.

It will become a major tourist attraction, attracting about two million people a year, each paying a penny to pass through, and will become the subject of popular songs.