Thames Tunnel

I've been fascinated by underwater tunnels my whole life. So when tickets were unexpectedly issued for new walking tours through Isambard Kingdom Brunel's Thames Tunnel between Wapping and Rotherhithe I leapt at them. Our hour under the Thames was a thrilling wander through history, where we followed the well hidden water pumping system down the tunnel's length, and discovered the 19th century brickwork had been concreted over to preserve the original design. It wasn't all covered mind you, as we discovered whilst being treated to rare insider knowledge and anecdotes shared by some delightfully geeky TfL volunteers. The tunnel was constructed between 1825 and 1843, is 396 metres long and was intended for horse-drawn carriages. Its currently used by the London Overground train network.