Dead End Street has a useful map showing the route of the old Fleet River and its tributaries, long ago buried in storm drains / large sewer pipes. The river used to flood, even into the 1930s.
It is said that you can still hear it gurgling past through a grating in Farringdon Road near the Guardian's old offices. And Diamond Geezer has tracked the entire course. In periods of heavy rain the river gives out into the Thames at Blackfriars Bridge. This image shows that site, from the Thames, c.1750.
2016: You want to see the River Fleet? Londonist have the post for you.
2019: The Islington Tribune reported that the River Fleet flows beneath the basement of an extension at the Sekforde pub and it is now being used to generate heating and also to cool the beer. Would we all had a river in the basement!
Comments are provided by Facebook, please ensure you are signed in here to see them