Portal:London/DYK/Thames Tunnels

Did you know...

...that there are seventeen tunnels underneath the River Thames in Greater London, with an eighteenth just outside?

...that the Thames Tunnel, completed in 1843, was the world's first underwater tunnel?

...that Tower Subway was the world's first underground tube railway, though not the first underground railway?

...that Greenwich foot tunnel is classed as a public highway, and is therefore kept open by law 24 hours a day?