<P> Up until 1750, London Bridge was the only crossing over the Thames, but in that year Westminster Bridge was opened and, for the first time in history, London Bridge, in a sense, had a rival . In 1798, Frankfurt banker Nathan Mayer Rothschild arrived in London and set up a banking house in the city, with a large sum of money given to him by his father, Amschel Mayer Rothschild . The Rothschilds also had banks in Paris and Vienna . The bank financed numerous large - scale projects, especially regarding railways around the world and the Suez Canal . </P> <P> The 18th century saw the breakaway of the American colonies and many other unfortunate events in London, but also great change and Enlightenment . This all led into the beginning of modern times, the 19th century . </P> <P> During the 19th century, London was transformed into the world's largest city and capital of the British Empire . Its population expanded from 1 million in 1800 to 6.7 million a century later . During this period, London became a global political, financial, and trading capital . In this position, it was largely unrivalled until the latter part of the century, when Paris and New York began to threaten its dominance . </P> <P> While the city grew wealthy as Britain's holdings expanded, 19th - century London was also a city of poverty, where millions lived in overcrowded and unsanitary slums . Life for the poor was immortalised by Charles Dickens in such novels as Oliver Twist In 1810, after the death of Sir Francis Baring and Abraham Goldsmid, Rothschild emerges as the major banker in London . </P>

When did london's population reach 1 million