A Pentagon official said it was concerned about 'any nation interfering with these cables].

Belfast - When your internet cable leaves your living room, where does it go? Almost everything about our day-to-day lives - and the broader scheme of human culture - can be found on the internet. But what is it physically?

And where is it really?

The internet, its material nuts and bolts, is an unexplored territory. Until now.

In Tubes, journalist Andrew Blum goes inside the internet's physical infrastructure and reveals an utterly fresh look at the online world we think we know.

It is a shockingly tactile realm of unmarked compounds, populated by a special caste of engineer who pieces together our networks by hand; where glass fibres pulse with light and creaky telegraph buildings, tortuously rewired, become communication hubs again.

From the room in Los Angeles where the internet first flickered to life, to the caverns beneath Manhattan where new fibre-optic cable is buried; from the coast of Portugal, where a 10,000 mile undersea cable just two thumbs wide connects Europe and Africa, to the wilds of the Pacific Northwest, where Google, Microsoft, and Facebook have built monumental data centres - Blum chronicles the dramatic story of the internet's development, explains how it works, and takes an in-depth look inside its hidden monuments.

For all the talk of the 'placelessness' of our digital age, the internet is as fixed in real, physical spaces as the railroad.

Like Tracy Kidder's classic The Soul of a New Machine or Tom Vanderbilt's recent bestseller Traffic, Tubes combines on-the-ground reporting and lucid explanation into an engaging narrative.

Sci-fi author William Gibson described cyberspace as a shared hallucination. Most people struggle to imagine what the internet's physical structure looks like.

Blum's first task is to disentangle our familiar conceptions about the internet from its actual cables, boxes and routers.

One such notion is the idea that the internet finds a route around censorship. This is true of the metaphorical overlay -take down a website and it can pop up elsewhere in an instant. But when it comes to the physical processes that prop up the metaphor, there is no going around them.

In reality, every bit of information sent between New York and London - every e-mail, Facebook status update, and bid on an eBay teapot - makes its way through the same thin 2,670 mile-long garden hose that submerges in Long Island and surfaces in Penzance. - Belfast Telegraph