Walking between two interesting pubs in Clerkenwell/Farringdon in London, the Jerusalem Tavern and the Gunmakers (they have up to date information on their beers on their website which is sadly incredibly unusual for most pub websites), I was quite struck by the topography around Farringdon Road. It was quite unusual for London and more like a city like Paris or Amsterdam as there were two roads that were only built up on one side with a large void between them of about 50 yards or so. Moreover, the ground gently rose on each side of the gap. The void was spanned by bridges that spans the Metropolitan line and the Thameslink railway line beneath but the geography looked very like a river valley.
Interestingly, a bit of research on the web shows that the tube and railway lines were actually built through the valley of the biggest of London’s hidden rivers — the Fleet. The river is contained in a storm drainage sewer that runs alongside the railway tracks. The Fleet itself is a fascinating subject — it rises in Hampstead and Highgate and passes into the Thames at Blackfriars via Kentish Town, Camden, St.Pancras, Farringdon, Clerkenwell, Smithfield, Holborn and (of course) Fleet Street. It is almost entirely covered over but water can be heard rushing down manhole covers at the time.
There’s a really excellent and comprehensive guide to the course of the hidden river on someone called London Geezer’s blog. It might make a good theme for a pub crawl?