Watch How London Was Built online: Episode 1 Bridges

Tunnels & Trains: From Brunel's Rotherhithe Tunnel to the King's Cross Channel Tunnel link Adam Hart Davis looks at the history of tunnelling in the capital. The earliest attempts were bids to link both sides of the Thames but they met with failure until Mark Kingdom Brunel, father of Isambard, was inspired by the teredo navalis woodworm which was then munching its way through the British fleet. The worm had two large teeth, which it used to chew through the wood before excreting what it had eaten behind it to create a kind of cement tunnel. Brunel's 'shield technique' worked but was incredibly slow, earning his Rotherhithe project the nickname 'The Great Bore'. The engineers who built the first tube lines opted instead for the cut and cover method which caused massive disruption on the surface. All deep tunnels have since used versions of Brunel senior's method. This episode also looks at the enormous Ring Main water system that encircles London, the recently closed Post Office underground and the Woolwich and Greenwich foot tunnels. The Railways - often called "London's iron roads" - have shaped the growth of the city from early 19th century onwards. Railway landmarks from the classic gothic lines of Sir George Scott's St Pancras Station to Norman Foster's cathedral-like Canary Wharf underground stop are examined. The programme also looks at the extraordinary logistics that were needed to create these new arteries into the capital and how the position of the mainline stations was dictated by the geography of the more upmarket parts of nineteenth century London.

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