In 1858 the ‘Great Stink of London’ made much of the city along the Thames uninhabitable.Between 1848 and 1854 nearly 25,000 Londoners died of cholera, a disease borne by foul water.Joseph Bazalgette saved the city, building sewers that would serve 4 million people and stop waste water emptying into the Thames.These sewers are still the backbone of London’s sewerage system today, but the city’s population is now approaching 10 million; the old sewers can’t cope and action needs to be taken to ensure that ‘The Great Stink’ never happens again.This is where the Thames Tideway Tunnel comes in: a £4.2 billion, 25km-long, 7.2m-diameter tunnel that will stop virtually all of the sewer overflows into the Thames and give us a cleaner and healthier river and city.This is the inside story on the tunnel, from the very start to breaking ground and all the steps along the way.Written by Phil Stride, a leading civil engineer, it is a unique chance both to see behind the scenes of an incredible civil engineering project and to meet the people who’ve taken it forward over the last ten years.