The Fleet - London's Underground River

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Below the sidewalks of London there is a remarkable network of tunnels and chambers, put in to place by Victorian engineers, the final step in a process which took centuries. For over a thousand years there had been a shipping dock at the mouth of the river - its name comes from the Anglo-Saxon fleot which means a tidal inlet. Yet it was not destined to persevere as a river in its own right.
(thanks Robert-John)The Presurfer