ZDNet.com.au's sister site silicon.com took a trip out to the east end of London, to the Thames Water depot near Stratford, for a rare trip down inside London's Victorian sewer network to see a much more high-tech network which it is now hosting — Geo's business broadband network. Here silicon.com editor Steve Ranger dons protective gear and gets ready to go underground.

Photos by silicon.com's Steve Ranger.

The view of the sewer from the ground above.

Visitors make their descent into the sewer network...

And the view from beneath. The broadband ducts are just visible in the top left of the picture.

It really doesn't smell that bad, either.

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 metres 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 fibre network, connecting into a major data centre on London's South Bank. And Icelandic Telco provider Siminn uses the network to provide a dedicated fibre connection between its two London data centres.

The fibre 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.