At the start of Victoria's reign, the north of England seemed out of control. Enormous industrial cities lacked basic amenities whilst many of their inhabitants lived in slums. David Dimbleby travels to Manchester, Leeds, Newcastle and the Tower Ballroom, Blackpool, to tell the story of Britain's greatest construction boom. Find out how factories, town halls, sewers, churches, hospitals and dance halls were built in a dramatic attempt to deal with the rapidly expanding urban population.