This sewer is a masterpiece of Victorian engineering–part of a giant project aimed at reducing the foul smells in the city and reducing the incidence of cholera–as reflected by this plaque. It still performs a vital role today.

The entry to the sewer seen from the ground above.

Visitors make their descent into the sewer network.

You won’t believe where they’ve laid a cable.

This is part of the Northern Outfall Sewer, designed by Joseph Bazalgette and built in 1862-3. It’s one of London’s six main interceptory sewers which run for almost 100 miles in total. The sewer flow is about knee height, though it can go much higher.

Geo bought its London sewer network from Thames Water and National Grid in 2006. It’s the only network to run through London’s sewer system, two meters below normal duct level, which the company reckons makes it highly secure and reliable–and less susceptible to workmen putting a pickaxe through it. You can see the cables at the top of the shaft.

The network–offering between 1 and 10Gbps–is for business customers. Geo recently announced further extension of its fiber network, connecting into a major data center on London’s South Bank. And Icelandic Telco provider Siminn uses the network to provide a dedicated fiber connection between its two London data centers.

The fiber runs through these cable ducts–which are too wide for rats to get its teeth around, so no danger of outages caused by hungry vermin.

Back to daylight.

Leaving the sewer in darkness again.