THAMES TIDEWAY TUNNEL (PB)

In 1858 the ‘Great Stink of London’ made much of the city along the Thames uninhabitable. Sir Joseph Bazalgette saved the city by building sewers that are still the backbone of London’s sewerage system. But with the city’s population approaching 10 million, the old sewers can’t cope. 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 London a cleaner and healthier river and city.