Documentary series revealing the demon diggers burrowing below our cities. In London, a tunnel boring machine faces immense challenges as it takes on Britain's deepest-ever tunnel. Meanwhile in Mexico, a giant mechanical worm makes the earth move just metres beneath the city's soaring skyscrapers.

We meet the largest land-based machines ever built - bucket wheel excavators. Their mission is to peel back the surface of the earth with each turn of their colossal parts but when you are battling mother earth, the fight is far from easy.

We climb aboard monster maritime machines that go where others fear to float. Man's desire for natural resources is insatiable, whether it is to power our homes, fuel our cars or build our skyscrapers, but with reserves on land running dry, we are now looking to the oceans to satisfy the needs of 21st-century living. This program showcases the cutting-edge machines at the forefront of this assault.